WO2002063173A2

WO2002063173A2 - Force generating apparatus

Info

Publication number: WO2002063173A2
Application number: PCT/GB2002/000436
Authority: WO
Inventors: Felix Isaac
Original assignee: Felix Isaac
Priority date: 2001-02-02
Filing date: 2002-02-01
Publication date: 2002-08-15
Also published as: WO2002063173A3; AU2002228195A1; GB0102731D0

Abstract

Apparatus (10) for applying a force to a body (22), comprises a floatation tank (52) with a floatation member (42) disposed therein and having a rigid force transmitting column (30) extending between the first body (22) and the member (42), wherein the flotation tank contains a known volume of liquid having a density greater than the floatation member, and the floatation member (42) is displaceable relative to and into the liquid within to a position past its natural equilibrium position at which the member would normally float, to create an increase in upthrust equal to the mass of additional displaced liquid, which increase in upthrust is transmitted to the first body (22) by the column (30). A force measuring device (50) measures the resultant downward force created by the relative displacement of the member into the liquid as indicative of the increased upthrust created by the apparatus. There is also provided a method of applying a force to a body using the above apparatus (10).

Description

Force Generating Apparatus

The current application is directed to a force generating apparatus, and more particularly to the use of increased buoyancy force resulting from a displaced liquid to create the desired force. More specifically, the apparatus further includes means for readily measuring this generated force in order to effectively apply such force.

It is generally understood, through basic physics and Archimedes principle, that a lightweight object will float due to the upthrust created thereon by the mass of the equivalent volume of displaced liquid, usually water, in which it floats, with the upthrust from the displaced liquid being equivalent to the weight of the floating object. Furthermore, it is understood that if additional downwards force is applied to such a floating object to displace it out of its equilibrium position (floating position) it will displace a greater volume of the liquid, whereby the additional displaced liquid will create an increased buoyancy force applied to the floating object which is equivalent to the weight of that floating object together with the additional applied force that has caused downward movement of such floating object. If this additional downward force is suddenly removed then the excess buoyancy force will cause rapid vertical displacement of the floating object back towards its equilibrium position. This is a well understood principle and can be illustrated taking a ball and holding it under water and then releasing it to see it shoot to the surface. However, while this effect is understood, it has not been put to practicable application in a controlled manner which allows for the force to be both used and measured so that the results of applying such force can be correctly analysed.

It is therefore an object of the present invention to provide a new method and apparatus for applying a force to a first body utilising the above principles and doing so in a controlled manner.

According to the present invention there is provided apparatus for applying a force to a body, comprising a floatation member to be placed in a liquid of known density, and a force applicator rigidly extending between the first body and the floatation member, in which the floatation member has a density less than the liquid, whereby the floatation member is displaceable relative to and into the liquid to a position past an equilibrium position at which the member would normally float, to create an increase in upthrust equal to the mass of additional displaced liquid, which increase in upthrust is transmitted to the first body by the force applicator.

Preferably, the apparatus will also comprise a floatation tank with the a floatation member disposed within the floatation tank and the floatation tank will hold a known volume of liquid, whereby the floatation member is displaceable relative to and into the liquid within the floatation tank to the position past an equilibrium position at which the member would normally float. Preferably, this apparatus is for applying a measured force to the first body and further comprising a force determining means, usually in the form of a force detecting means, and in particular for measuring weight (such as scales), with the floatation tank being mounted on this force detecting means for measuring an increase in force exerted by the floatation tank during relative displacement of the member and the liquid past the equilibrium position, wherein the measured increase in force is indicative of the force applied to the first body by the force applicator.

Alternatively, the force determining means may comprises a calculating means, such as a computer or other central processing unit, for applying a known algorithm to measured physical values of the apparatus to calculate this force.

Usually, the first body is restrained from displacement relative to the equilibrium position of said floatation member and/or restrained from displacement relative to the force measuring apparatus

Preferably, the flotation member may be restrained from displacement relative to the flotation tank, whereby the relative displacement between the floatation member and the liquid is effected by increasing the depth of the liquid liquid in the floatation tank. Alternatively, the floatation member may be displaceable relative to the floatation tank to effect relative displacement between the floatation member the liquid.

Usually, the force applicator is releasably secured to the first body and, preferably, the length of force applicator between the first body and the floatation member is adjustable.

It is also usual for the first body to comprise an elongate horizontal member, which first body may be integral with the apparatus or may be secured or positioned relative to the apparatus to be acted thereon by the applied force. In such embodiments, it is usual for the force applicator to be longitudinally displaceable along this first body.

Preferably, the apparatus will also comprise a base member on which the floatation tank is mounted, with the first body optionally rigidly secured to this base member.

It is also possible that the floatation tank is mounted on a fulcrum bar so as to be balanced thereon when the tank is empty.

In addition, it is also optional for the apparatus to comprise engagement means optionally and releasbly engageable between the tank and the floatation device to secure the tank to the device. In addition, there is also provided according to the present invention, a method for applying a force to a body, comprising the steps of:

placing a floatation member within a floatation tank, providing this flotation tank with a known volume of liquid having a density greater than the floatation member, effecting relative displacement between this floatation device and the liquid to effect relative displacement of the floatation device into the liquid within the floatation tank to a position past an equilibrium position at which the member would normally float, to create an increase in upthrust created by mass of additional displaced liquid and further transmitting this increased upthrust to the first body by a force applicator rigidly extending between the first body and the floatation member.

Preferably, this method will allow the for application of a measured force to the first body and further comprising the step of determining the force, usually by mounting the tank on a force detecting means, such as scales, and measuring an increase in force exerted by the floatation tank during relative displacement of the member and the fluid past the equilibrium position.

Alternatively, the force may be determined by calculation, by applying a known algorithm to measured physical values of the mass of the liquid, size of the tank and the height of the liquid within the tank to calculate this force. Usually, the method will further comprise the step of restraining the first body from displacement relative to the equilibrium position of the liquid at which the body would normally float.

Preferably, the volume of liquid within the floatation tank will be increased to resultantly effect an increase in the upthrust on the floatation member.

Further according to the present invention, there is also provided stress testing equipment comprising apparatus for applying a force to a body as discussed above.

Still further according to the present invention there is provide display apparatus for demonstrating upthrust or buoyancy forces exerted on a floating member, comprising the apparatus for applying a force to a body as discussed above, usually for demonstrating Archimedes Principle.

This display apparatus is also applicable for demonstrating Newton's Third Law of Motion.

In addition, and according to the present invention, there is also provided a system for storing potential energy comprising apparatus for applying a force to a body as discussed above, wherein the first body is restrained from displacement relative to the equilibrium position of the floatation device.

Preferably, this system for storing potential energy may be utilised in a power source, and such power source may preferably be used in an engine for converting potential energy into kinetic energy.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying illustrative drawings in which:

Figure 1 is a perspective front view of an apparatus according to the present invention in part section; and

Figure 2 is a perspective rear view of a support frame of the apparatus of Figure 1 with force measurement equipment and force generating equipment removed; and

Figure 3 is the front perspective view of the frame of Figure 2 together with the force measurement equipment; and

Figure 4 is the perspective view of the apparatus of Figure 3 with the floatation tank in place; and Figure 5 is the front perspective view of the apparatus of Figure 1, in part section, with the force measuring device and floatation tank removed; and

Figure 6 is the perspective view of the apparatus of Figure 1 in a second operational configuration; and

Figure 7 is the perspective view of the apparatus Figure 7 with the floatation tank shown in part section; and

Figures 8a to 8c show schematically the principle of buoyancy according to

Archimedes Principle utilising the apparatus of the current invention; and

Figure 9 is a partial schematic view of the apparatus of Figure 6 in a third operational configuration.

Figure 1 shows a preferred first embodiment of the present invention of a force generation and measurement device (10) which basically comprises a base unit or platform (12) having rigidly and securely attached thereto two upright support columns (14) and (16). The inwardly directed surfaces of the support columns (14) and (16) comprise support means (20), which in this specific embodiment comprises a pair of tracks (20), for slideably receiving a beam member (22) towards the upper ends (18) of said columns (14) and (16). The beam member (22) is held in rigid fixed engagement between the columns (14) and (16) by use of pins (24) passing through coaxial holes in the tracks (20) and corresponding holes (not shown) through the beam (22). As can be seen from Figure 1 two pins on each support column are used to engage the beam to hold it in rigid engagement. It will be appreciated that there are other methods of supporting and retaining the beam in this desired position, the simplest being to simply pass the beam through approved apertures in each of the columns (14, 16). However, the invention is not intended to be limited to a specific form of support means for such beam (which may be fixed or adjustable) and the use of tracks as described provides for allowing the beam to be adjustable vertically along the support columns (by use of an array of holes (not shown)).

Mounted on the beam (22) is an adjustable collar mechanism (24) which comprises a beam engaging mechanism (26) (Figure 2) which effectively comprises a rectangular aperture for close co-operating receipt of the beam member which is passed therethrough. This allows the column (24) to freely slide along the beam (22) but to be restrained from relative vertical displacement thereto.

Integrally formed with the beam engaging mechanism (26) is a transversely extending aperture (28) (see Figure 4) for slideably receiving a force transmitting column (30), which column (30) is substantially rectangular in cross section for complimentary sliding receipt within the correspondingly shaped and sized aperture (28). This column (30) is substantially rigid. As can be seen from Figures 1 and Figures 4 the collar (28) has, on a rearwardly directed surface thereof, a vertically extending array of holes (32) communicating with the aperture (28), whereby the column (30) has a complimentary vertically extending array of holes (34) such that a dowel rod or pin (36) may be inserted through one of the holes of the array (32) and also to be received in one of the holes of array (34) to effect engagement between the collar (24) and the column (30) so as to restrain the column (30) in a pre-determined position fixed vertically with respect to the beam (22). Of course, the vertical position of the column (30) is adjustable by removing the dowel pin (36) and realigning the array of holes (32) and (34) before reinserting the pin with the column in a different vertical position ie. compare figures 1 and 2.

In addition, and referring to Figure 2 showing the rear of the apparatus, the rear side of the collar (24) comprises at least one further single hole communicating with the aperture of the beam engagement mechanism (26), with the beam (22) itself further comprising a substantially horizontal array of holes (38) so that a second dowel pin (40) can be passed through the hole of the beam engaging mechanism (26) to engage with one of the holes of the array (38) to restrain the collar in a pre-determined horizontal position along the length of the beam.

The use of the array of holes and dowel pins to effect the restraint of both the column (30) and the collar (24) on the beam (22) is simply one embodiment of a restraint mechanism of which many alternatives are envisaged. For example, friction fit restraint mechanisms could be used (such as screw threaded pressure pads used to frictionally engage between the collar and the respective beam or column (30)) or alternatively, a mechanical latch mechanism could be used for adjustable restraint of these members. In a more complex embodiment (not shown), engagement between the collar and the column (30) or beam member (22) may be effected by use of motor driven cogs allowing for power driven adjustments of the various positions of the column and collar relative to the beam (22). All such variants are clearly envisaged as being standard adjustable restraint mechanisms well understood in the art and will not be described in any great detail further. However, the current invention is not intended to be limited to any specific type of vertical or horizontal restraint mechanism.

Mounted on a lower end of the force transmitting column (30) is a first flotation member (42) which effectively comprises a rectangular watertight perspex box having an open upper end (43) into which the column (30) extends to engage with an engagement mechanism (44) to optionally restrain the flotation member (42) in engagement with the column (30) (Figure 5). As can be seen in Figure 5, (wherein two of the walls of the member (42) have been removed for clarity), the column (30) has at a lower end thereof a hole extending therethrough (not shown) for receipt of a bolt member (46) which also extends through two upright members (48) integrally formed with the base of the flotation member (42) to releasably restrain the member (42) in engagement with the column (30). It will be appreciated that by removing the bolt (46) will the force transmitting column (30) will be disengaged from this member (42).

Referring back to Figure 1, the apparatus (10) further comprises a force measuring device (50) which in its simplest form may comprise a set of weighing scales having a substantially flat weighing area (not shown). Preferably such scales will be electronic to allow for ease of reading and to be re-set at zero in order to start measuring additional forces applied thereto. Such scales are commonplace and may be purchased in the majority of conventional hardware stores and their operation is not important to the current invention save for their availability to measure weight (and, thus, force) applied thereto. Alternative force measuring devices may be utilised to achieve the same results and are considered to fall within the scope of the current invention.

The scales (50) sit on the base (12) and support thereon a flotation tank (52) which is substantially rectangular in shape having an open upper end (53). In Figure 1, two sides of this flotation tank (52) are shown removed for viewing the floatation member (42) accommodated therein, this flotation tank being shown in its entirety in Figure 4. Effectively, in a first embodiment or application, this flotation tank (52) is balanced on a substantially flat surface of the scales (50) and substantially surrounds the floatation member or box (42). In its preferred embodiment the flotation tank (52) comprises transparent perspex material (for viewing the liquid and flotation member therein) and is formed so as to be watertight.

In practice the apparatus (10) will be set up as in figure 1 and a liquid of known density (usually water) will be added to the watertight floatation tank (52) and the floatation member, free of contact with the side walls of the tank (52) will be immersed in and is able to freely float in said liquid (provided sufficient liquid has been inserted to create sufficient buoyancy) - also refer to Figure 8b. By use of the dowel pins (36, 40), the column (30) and floatation device can then be secured from further displacement in several different and controlled positions as will be discussed below.

In the initial configuration of the current invention, the floatation tank (52) will be initially set up on the scales (50) so that the scales (50) measure the weight of the floatation tank. The floatation member or box (42) is then placed within the floatation tank (52) and their combined weights measured, whereby the deduction of the weight of the floatation tank (52) will result in a measurement of the weight of the floatation member (42). Finally, the apparatus may be set up as shown in Figure 1 with the force transmitting bar (30) passed through the collar (24) (although not restrained thereby) whereby the additional weight or downward force (column 30) can also be measured by measuring the total reading on the scales (50) and deducting the relative force or weight applied by the member (42) and tank (52). (For practical purpose and measurements the combined weight of the floatation member (42) and column (30) are used when reference is made to weight of floatation member). This is merely to establish set up measurements of the various components of the apparatus.

Basically, weight is a measurement of force derived by the action of gravity on the mass of a body. Thus, weight = m x g = F (where m = mass, g = acceleration due to gravity and F = force (Newton's Second Law).

Furthermore pressure (P) = force per unit area (F/A). Therefore since we know that force = mg then pressure: P = mg/A.

However, we also know that density, p = mass per unit volume (m/V), from

which

m =. pV

Thus, pressure can be expressed as

P = F/A = mg/A = p g V/A = p g h (since volume = h (height) x A.

As such, the pressure P within a tank of water or other fluid can be expressed as

equivalent to p g h, and is thus directly proportional to the height of the liquid.

With this basic background knowledge the operation of the current invention will now be described in particular with reference to the schematic drawings shown in

Figures 8a through 8c. In its simplest operation the floatation member (42) and bar (30) are removed or held sufficiently remote from the base of the tank (52) that they do not engage with either the tank itself or the liquid (usually water) placed therein. This scenario is shown schematically in Figure 8a whereby it will be appreciated that the measurement on the scales (50) of force (or weight) Fl in this particular instance will equate to the combined weight of the water or liquid inserted into the floatation tank (52) and the weight of the tank (52) itself. The pressure of the liquid within this tank can expressed as

PI = pghl = Fl/A (where A = area of base of tank (52)).

If the floatation member (42) with the connected bar (30) (via engagement mechanism 44) is lowered into the floatation tank (52) (illustrated schematically in Figure 8b) then the member (42) will sink until it reaches an equilibrium position whereby the mass of the displaced liquid in which the member (42) sits will create a buoyancy force equivalent to the downward force (or weight) of this member

(42) and bar (30). The equilibrium position is shown schematically in Figure 8b where it is seen that the level of the liquid in the tank (52) rises to a level h2

whereby the pressure P2 increases to pgh2. In effect what is seen is that the

weight of the member (42) is added to the weight of the water and floatation tank (52) to give a combined force reading F4.

In addition, it will be appreciated that the buoyancy force F2 is equal to the weight F3 of the member (42) (shown in balanced equilibrium in Figure 8b). It is now possible to calculate the change in weight of this system (ie. the force or

weight measured by the scales (50)) whereby the change of force (Δ F) is equal to

the mass of the member (42) ie. Δ F = F4 - Fl which is equal to

P2A - P1A = (P2 - P1) A = (h2pg - hlpg) A

(h2 - hl) pgA

thus it would be possible to calculate the increased measurement on the scales (50) by simply measuring the variants in height of liquid in the floatation container (42).

Referring now to Figure 8c an extra downward displacement force F5 is applied to the floating member (42). This could take the form of the insertion of a additional mass such as a weight or by the application of an exterior force such as a user pushing down on the inside of the member. Displacement of the member (or container) (42) deeper into the liquid within the tank (52) results in additional displacement of the liquid to a third height h3 when a second "forced" equilibrium position is again achieved. This additional height of liquid with an increased mass of displaced liquid results in an increased buoyancy force F2 equivalent to the combined weight F3 and applied force F5 to achieve this secondary equilibrium. Thus the application of additional force F5 is equivalent to an effective increase in the weight and mass of the container (42). Thus it is expected that the overall measured force F6 should also increase by an equivalent amount F5. In equilibrium F3 equals F2 plus F5, therefore the combined force F6 will equal the weight of the tank (52) weight of the liquid, weight of the container (42) and the additional force F5. Since the container is still buoyant (floating), Archimedes principle still applies, thus it is now possible to calculate and measure the change

in force Δ F * as force increases from F4 to F6 , wherby

Δ F * should equate to F5 as follows:

Δ F * = F6 - F4

= P3A - P2A = (P3 - P2)A = (h3pg - h2pg) A

= (h3 - h2) pgA

Thus, it is clear that any additional increase in applied force (F5) to a floating object will equate to a measurable increase in the height h3 of the liquid within the floatation tank (52) which can thus be measured and F5 calculated.

Whilst the above example discusses the application of an external force F5 to displace the floating container downwardly from its equilibrium position in Figure 8b, it is equally possible and clearly envisaged by the embodiment shown in Figure 1 that the floatation member (42) is fixed relative to the beam (22) (and thus relative to the base of the floatation tank (52)).

In Figure 8b it is then secured from further upward movement by attachment to the beam. Additional liquid is then added to the tank (52), and since the member (42) being restrained from its normal equilibrium or floating position, and is effectively displaced relatively downwards compared to its normal equilibrium position for the new volume of liquid. Since the member (42) is still floating Archimedes principle still applies. The increase in the level of the liquid in the tank, surrounding the member (42), is greater than would be expected if the member (42) was freely able to float, this additional height resultant from and creating an additional buoyancy force created by the "relative" downward displacement of the member (42) past its natural equilibrium position, and can be equated to the effective additional force F5 that would be necessary to displace the member (42) to the position in which it has been forceably held by engagement with the rigid member (30) with the beam member (22).

In fact, a force is applied to the floatation member (42) by virtue of a reaction force exerted from the beam member (22) through the support (30) to the member (42) which reaction force is directly equivelent to the increase in buoyancy force resultant from the increase mass of the displaced liquid over that which would be expected if the member (42) was able to reach its natural equilibrium position. Thus the reaction between the support (30) and the beam (22) clearly demonstrates Newton's Third Law "for every action there is an equal and opposite reaction". This reaction force is directly applied to the floatation member (42) by the column (30) in this secondary equilibrium position and can be equated to the force F5 as discussed with reference to Figure 8c.

Thus, in the situation where a known volume of additional liquid having an extra mass is added to the apparatus, then if there was no restraint on the floatation device (42) there would simply be an increase in the weight of the apparatus equated to the additional mass of water. However, the force in fact measured by the scales (50) will not only include the additional mass of water but the additional force F5 applied by the reaction between the support (30) and the beam (22) and transmitted to member (42).

To further explain this, the increase in volume of water or liquid in the container has increased the effective mass of such liquid. Thus in order to determine the increase in upthrust or buoyancy force created by the addition of the water it is first necessary to calculate the theoretical height of the level h2 for the new volumes of added liquid ie. to calculate the height of liquid at the natural equilibrium position. Thus referring again to Figure 8b the measured force F4 equals mass of tank (52), mass of the container (42) and mass of the liquid. Thus in order to calculate the h2 height for the new mass of water at a natural equilibrium then F4 = weight of container (constant) plus weight of water (m g) plus weight of tank. Set ml (constant) as weight of container and m2 as mass of liquid (measured before insertion into the tank). Thus

F4 = (weight of tank) + mlg + m2g = (ml + m2)g .

Where (ml+m2)g is equal to P2A. (Force exerted by water and member (42))

Now P2 = h2pg . Now, by ignoring the constant weight of the tank itself which

can be deducted from F4 to create the force F4*, (ie. the force due purely to the weight of the container (42) and the weight of the water) we can achieve the equation:

F4* = h2pgA = (ml + m2)g

Threfore, h2 = (ml + m2)/ pA

since ml, m2 and A are known, p is constant, the theoretical h2 of the equilibrium

position for any known mass of water can thus be calculated. Once the theoretical value of h2 is known this can be supplemented into the previous equation for measurement of the force

ΔF = F6 - F4 which equals F5

Now, according to earlier calculations,

F5 = (h3 - h2) p g A Therefore,

Δ F = (h3 - (ml + m2)/ p A) p g A

.". ΔF = h3pg - (ml + m2)g

Again h3 can be measured, p and g are constant, ml and m2 are known from

earlier measurements thus the force F5 can be calculated.

As such, the resultant Force F5 as shown in 8c can be achieved by either displacing the container past its equilibrium deeper into the liquid or can be achieved by restraining displacement of the container (42) past its equilibrium point whilst additional water is added.

In all situations it is seen that the force F5 can be either measured as an appropriate increase in weight or readily calculated by implementation of the above algorithms, manually or by use of an appropriate computer or other central processing unit. If electronic scales are utilised for known masses of liquids, the apparatus could be automated by utilising such a computer to determine the appropriate forces created or, possibly, required to be effected by the apparatus.

In both the above situations the resultant additional displacement force F5 is

equated to the increase measurement Δ F, thus from either measurement of

increased weight of the scales (50) or measurement of height h3, the reaction force applied to the beam (22) through the force transmitting column (30) is easily calculable.

Alternatively, it is possible that the beam itself may be lowered, when secured to the column (30), to effect the increase in downward force F5 on the container

(42), where the liquid volume in the system is maintained constant. Similarly, the scales (50) and the tank (52) may be raised relative to the fixed beam (22) to achieve the same results.

All of the above methods will achieve the same principle of forcing the member or container (42) past its natural equilibrium point deeper into the liquid to increase the head of water surrounding that liquid and to increase the resultant upthrust (buoyancy) to reach secondary equilibrium position as shown in Figure 8c, from which the additional force F5 can be calculated or measured, and where applicable, this force F5 equating to the reaction force applied to the beam (22).

Further, whilst the current embodiment utilises dowel pins or rods to effect the force transfer from the column (30) to the beam (22) it will be appreciated that the beam could be integrally formed with the member (30) or any other form of connection achieved between the two members to allow the appropriate force transmission. In its simplest form the current invention provides a means of providing an upward force against a fixed member (here a beam (22)), which force is readily measured and variable. Practicable applications of such a force transmitting device could be in the stress testing of support members used in buildings etc. so as testing could be destructive or non destructive.In such use, the apparatus (10) is altered and the beam (22) is replaced by the object to undergo the application of force, with the column (30) being attached directly to such object, the resultant reaction force F5 applied thereto by the object may be used to test the strength of that object, how strong is the seating of that object (ie. Could it be unseated and what force F5 would be required) or even to simply measure the weight of that object in sufficient force F5 is obtained to lift the object.

In the application to non destructive testing, a maximum predetermined force (F5) could be applied to ensure that the beam does not fail. Alternatively in destructive testing, increased liquid could be applied to a system of appropriate size to gradually increase the calculable force F5 and the appropriate reaction force on the beam (22) until such beam fails. At all times force F5 could be carefully predetermined and/or measured by using the foregoing measurements, calculation and/or algorithms.

As a result of the above calculations, it is possible for any known mass (or volume) of liquid (preferably water) to be added to the system with the floatation member (42) secured from relative displacement by connection to the beam (22) that the theoretical equilibrium height of that mass of water can be calculated as h2, whilst the measured value of h3 from the apparatus can be utilised to calculate the upthrust force which equates to the reaction force F5 which should be reflected

by the ΔF measurement. Thus, the current apparatus will allow the additional

buoyancy force created by the downward displacement of the floatation member

(42) from its equilibrium position to be either calculated or measured directly by the scales and this additional buoyancy force equates to a reaction force exerted on the beam (22). This upward force having been accurately measured can thus be used for destructive or non destructive testing by the application of a force on a selected object. An example of such non destructive testing could be in the building industry whereby it is desired to apply a non destructive test to floors or ceilings to determine whether or not they meet minimum load bearing requirements. Here a pre-set minimum of force could be applied by equipment (of the current invention) of appropriate size, by securing the floatation member to such flooring or ceiling beams from below. A known force can then be applied by applying an appropriate volume of water to create sufficient upthrust and thus reaction force on the beam. Such equipment would be very useful in the building industry or in many other environments since it is easily portable (once the water is removed) and utilises a commonly available substance, (ie. water) to apply the force which water may be readily disposed of. Furthermore, since the involved mathematics are extremely simple (allowing a simple measurement on a conventional scales to be utilised to measure the force) the apparatus is extremely simple in construction and use. Still further, an additional advantage of the current embodiment described above is its versatility in use by providing for relative lateral displacement of the floatation member (42) within the floatation tank (52) (provided there is no contact between floatation tank and floatation member) to an "off-center" position

(see Figures 6 and 7) without affecting, in any manner, the upthrust created by the displaced water on the member (42)). This is best explained with reference to Figures 6 and 7 (showing a second operational configuration of the invention and apparatus (10)) which demonstrates a peculiarity of this type of apparatus and system.

Referring now to Figure 6 the apparatus shown is identical to that shown in Figures 1 to 5 with the exception that a fulcrum device, in particular a fulcrum bar (60) (or pivot bar) is provided between the flat surface of the scales (51) and the base (61) of the floatation tank (52). This fulcrum bar (60) is provided to extend across the base of the floatation tank (52) centrally so that when the tank (52) is empty or loaded purely with liquid, it is perfectly balanced on this fulcrum bar (60). The loads supplied by the tank in the previously described situations are now transferred through the fulcrum bar to be measured on the scales (50) and do not effect measurements save for the additional weight of the fulcrum bar itself.

When the floatation member (42) is deposited so as to freely float to its equilibrium position within the tank (52) it is understood that due to the relative displacement of the liquid caused by such floatation member (42) that the system remains in equilibrium and equally balanced about the fulcrum irrespective of whether the member (42) is disposed directly above the fulcrum (as in Figure 1 - although no fulcrum shown in Figure 1) or is disposed to one side (Figures 6 and 7). This is readily understood in that the pressure within the fluid remains constant and equal on all areas of the base of the floatation tank (52). It may also be readily understood by the concept that at any given point on the base of the tank (52) there exerted an equal downward force, whereby underneath the container (42) the downward force can be considered due to the head of water above that point plus the weight of the tank above that point, whereas in the area of additional displaced liquid, there is an additional height of water resulting in additional force, equating to the downward force at a point beneath the member (42). However, it is understood that the system remains in equilibrium throughout due to the equalisation of pressure.

Secondly, when the additional downward force F5 is applied to the floatation tank (52) in any of the manners described above (but especially as a result of the reaction force between the force transmitting support bar (30) and the beam (22)) this merely serves to provide an additional downward force (F5) resulting in additional liquid displacement within the system. Even with this additional liquid displacement the system remains perfectly balanced about the fulcrum irrespective of the position of the floatation member (42). Similarly, the reaction force exerted on the beam member remains constant irrespective of the position of the floatation member (42) within the floatation tank (52) (Pressure P3 remains equal throughout the system). Thus, as previously described, the bar (30) may be longitudinally displaced along the beam (22) without any effect of the reaction force exerted on the beam member and thus the system provides for a means of applying a force along a longitudinal beam (22) without the necessity of adjustment of the main floatation tank (52) but merely by allowing the collar (14) to be slideably displaced along the beam. This provides a significant advantage whereby once an apparatus of this type has been set up it does not have to be moved to maintain an equal reaction force on the beam member (22) irrespective of lateral displacement of the container (42) within the tank (52) and thus allows for testing of such beam in many various positions. Again, this provides a significant advantage with destructive and non destructive testing utilising this apparatus, in that the system may be set up and the item to be tested may be tested in various positions without readjustment or movement of the force generating floatation tank (52) and liquid therein which would be both hard work and time consuming.

Referring now also to Figures 1 through 7 and 9, it can also be seen that there are holes (62) through the upper portion of the walls of the floatation member (42) and corresponding holes (64) in the upper regions of the walls of the floatation tank (52). These are merely illustrative of the general concept which will now be described. When the system is held in equilibrium as shown in Figure 8c (whereby the floatation member (42) has been displaced past its equilibrium position to a second position by the application of a reaction force F5) the floatation member (42) can be rigidly and securely connected to the floatation tank (52) by passing rigid rods (105) - see Figure 9 - between the holes (62) in the floatation member with aligned holes (64) in the floatation tank (52) creating an effective rigid engagement between the member (42) and tank (52). It will appreciated this is simply one possible embodiment for effecting such rigid connection and many other clamping mechanisms could be equally applicable to this particular system to simply effect rigid engagement between the tank and floatation member to prevent relative displacement. In effecting this engagement no initial effect is seen on the apparatus (10) since the various forces still remain constant. However, in the event that the floatation member (42) is not centrally positioned over the fulcrum bar (60) (ie. it is displaced in the position as shown in Figure 7), then should the bar (30) be disengaged from the beam (22) (ie. by removing the appropriate dowel rod (36)), then the reaction force F5 between the container (42) and beam (22) is removed from the system and the additional upthrust on the floatation member (42) is then transmitted, by the rigid connections of the bars (105) , to the tank (52) creating an additional upthrust on the side walls thereof equal to the upthrust created by the remaining additional displaced body mass of liquid, creating a moment about the fulcrum (62) which will displace the apparatus out of balance on the fulcrum bar (60) causing the floatation tank (52) to thereby tip about this fulcrum with that half of the tank containing the floatation member moving upwards. The additional moment force exerted on the tank can be equated to the previously measured force F5. The exact effective moment created by such reaction is dependent on the distance of the floatation member from the central fulcrum. Subsequently, if engagement between the floatation member and floatation tank is removed, the floatation member (42) will return to its equilibrium position freely floating within the tank, the moment will be removed and the apparatus can be returned to a balanced position if re-distribution of the liquid is achieved. This anomaly is useful in demonstrating the reaction force exerted by the fixed beam to the overall balance of the system.

With reference to Figure 9, if will also be appreciated that if the member (42) is secured in a central position over the fulcrum (60) when attached to the tank (52) such that the rods (105) create an upthrust on the tank walls either side of and equidistant from the fulcrum (60) then the resultant moments created either side of the fulcrum serve to negate one another and the apparatus remains balanced.

In this manner, the apparatus described above can also serve as a very useful teaching aid or demonstration apparatus for explaining several basic principles of physics notably Archimedes' Principle, Newtons Second and Third Laws, and the creation of moments about a pivot point or fulcrum. What is specifically useful in such a demonstration model is that such laws of physics are generally difficult to demonstrate in a teaching environment and the above apparatus provides a useful visual aid to demonstrate forces, which are not easily visualised by students, in a highly graphic manner and which also allows forces to be readily calculated from standard physics equations and can be readily tested by the simple measurement exacted on the scales.

The basic apparatus described above is merely by way of an example only and there are significant variations to this apparatus which can be achieved to vary the application of the invention. In particular, the upthrust that can be created is dependent on the mass of water displaced from a normal equilibrium position to a forced equilibrium position ie. from Figure 8b to 8c. An appropriate selection of the size and shape of the floatation member can be utilised to create significant force. For example, if a very deep, lightweight (but strong) floatation container is used then more liquid can be displaced having a greater mass resulting in a greater upthrust. Obviously this apparatus does create an increase in pressure within the liquid and thus it is important that the strength considerations of the apparatus should also be taken into consideration and it may be necessary to introduce lightweight reinforcing struts within the floatation member (42) to create additional strength, preventing its side walls collapsing. Such struts could comprise known lightweight materials such a fibreglass rods or other known materials commonly available. Similarly, the floatation tank (52), whilst described in this preferred embodiment as clear perspex to allow its specific application as a visual teaching aid, the weight of this apparatus is only limited by its practicable applications and the necessity for it to be portable in certain circumstances. Therefore any perceived material including steel could be utilised to provide sufficient strength to contain liquid at the increased pressures required to provide increased reaction forces where such high reaction forces, are required for a specific application.

Whilst the preferred embodiment has described the use of a specific arrangement in which the support columns (16 and 18) are connected to a base unit (12) on which the entire apparatus sits, this is not essential to the operation of the invention. The above preferred embodiment utilises the described configuration to provide an effective "infinite mass" to the support beam. Basically, if there is a reaction force applied by the force transmitting column (30) to the beam (22) this is transmitted to support columns (14 and 16). This reaction force can never be sufficient to move the beam member (22) upwards (for theoretical purposes assuming the beam has infinite strength) since any upthrust (F5) must be less than the measured force on the scales (50) due to the additional weight of the apparatus F6. Thus any reaction force (F5) will always be less than the measured force F6 simply due to the additional weight of the apparatus itself, which force (F6) anchors the column (14 and 16). Thus the upthrust is always trying to lift a mass (in beam (22)) which is effectively greater than the upthrust that can be created by the apparatus.

However, it is also envisaged within the scope of the invention, that the beam member (22) may be vertically displaceable relative to support beams (14 and 16). In this manner, the apparatus could be used as a lifting apparatus whereby additional upthrust and reaction force F5 on the beam member (22) could be created to overcome the weight of the beam member (22) or any frictional restraining force exerted thereon to move the beam member (22) upwards under influence of the reaction force (F5) and thus the upthnist created by the additional displacement liquid in this system. Thus, the present invention also has application as a lifting device. If the beam (22) were also to be maintained in engagement with the support bars (14 and 16) but these support bars (14 and 16) removed or disengaged from the base (12) then such a lifting device would not be limited to simply displacing the beam member (22) upwards but could also be used to lift loads borne at any position on the support beams (14). Again, if the weight of the object to be lifted (inclusive of beam and all support columns (14 and 16)) is known, then the required reaction force on the beam sufficient to lift "uch weight can again be readily calculated and appropriate liquid added to the system to provide the required upthrust and displacement.

An additional utilisation of the current invention would be the creation of a hydraulic engine. Referring back to Figure 8c it would be understood that in this equilibrium position there is an upward reaction force F5 exerted on the beam resultant from the additional buoyancy force created in this situation. Should the force transmitting column (30) be disengaged from the beam (22) in this configuration the resulting upthrust on the floatation member (42) will cause a rapid upward displacement of the member (42) and column (30) relative to the tank (52) and the beam (22), in order for the system to revert to the equilibrium position shown in Figure 8b. In this situation this rapid displacement of the column (30) could^' be used to drive an electrical generator, for example, by simply connecting the column (30) to a standard linear to rotational motion conversion mechanism, as are standard and well understood in the art. Thus, such a rotary output could then be used to drive an appropriate generator in a conventional manner. A specific use of this rapid linear motion as a power source is again not limited to any specific embodiment but it will be appreciated that by using standard engineering and electronic techniques, any rapidly moving body creates a power source that is very readily convertible to various forms of energy including electrical and mechanical energy.

Additionally, once the floatation member (42) has reacquired its natural equilibrium position (Figure 8b) it could then be reconnected to the beam member (22), the liquid in the tank (52) subsequently removed (ie. by opening a tap (not shown) at the base of the tank to allow the liquid to drain under gravity) thus creating further potential energy due to the weight of the container being supported by the beam (22). Again, if the attachment between the bar (30) and beam (22) is removed the container and bar (30) will fall under the action of gravity again creating a rapid linear displacement of the bar member (30). Again, this rapid linear displacement could be utilised as a power source. Subsequently, the bar (30) could be reattached to the beam member (22) and the cycle repeated. In this manner, the current apparatus can be utilised as a hydraulic engine for converting energy into an alternative form. In particular an engine of this type could be used for the creation of "tidal energy" whereby there is a natural variation in the height of liquid on an immense natural scale whereby a series of floatation members (42) could be arranged in sequence on a sufficiently rigid and appropriately sized beam (22) to utilise the above invention to create potential energy which can be converted into other forms of various energy, and notably electrical energy. In such a situation the use of floatation tanks would be optional (although where used could be adjustable to allow the sea water to flow in and out in a controlled manner to apply the principles discussed above). However, where such tanks are not employed, the support beam would be held rigid and restrained from vertical displacement so that an increase in the tide level would create an additional upthrust on the support beams which would then be released from engagement with the beam to create movement which could be converted to electrical energy using standard techniques. In this situation, if measurement of force exerted on the beam is required a force detection means could be employed either between the column (30) and the beam or between the column (30) and the base of the member (42) (eg. a scales) which would allow direct measure the reaction force created by additional upthrust.

The apparatus demonstrated in Figure 8c effectively provides a system for storing potential energy, which itself could act as a power source in an engine for converting potential energy into kinetic and, subsequently, electrical energy.

Claims

1. Apparatus for applying a force to a body, comprising a floatation member to be placed in a liquid of known density, and a force applicator rigidly extending between said first body and said floatation member, in which said floatation member has a density less than said liquid, whereby said floatation member is displaceable relative to and into said liquid to a position past an equilibrium position at which the member would normally float, to create an increase in upthrust equal to the mass of additional displaced liquid, which increase in upthrust is transmitted to said first body by said force applicator.

2. Apparatus as claimed in claim 1 further comprising a floatation tank with said floatation member disposed within said floatation tank and said flotation tank holding a known volume of liquid, whereby said floatation member is displaceable relative to and into said liquid within said floatation tank to said position past an equilibrium position at which the member would normally float.

3. Apparatus as claimed in either of the preceding claims for applying a measured force to said first body and further comprising a force determining means.

4. Apparatus as claimed in claim 3 wherein said force determining means comprises a force measuring means and said floatation tank being mounted on said force detecting means for measuring an increase in force exerted by said floatation tank during relative displacement of said member and said liquid past said equilibrium position, wherein said measured increase in force is indicative of the force applied to said first body by said force applicator.

5. Apparatus as claimed in claim 4 wherein said force measuring means comprises apparatus for measuring weight .

6. Apparatus as claimed in claim 3 wherein said force determining means comprises a calculating means for applying a known algorithm to measured physical values of the apparatus to calculate said force.

7. Apparatus as claimed in any one of the preceding claims wherein said first body is restrained from displacement relative to said equilibrium position of said floatation member.

8. Apparatus as claimed in claim 4 or any one of claims 5 to 7 when appended to claim 4 wherein the first body is restrained from displacement relative to said force measuring means.

. Apparatus as claimed in claim 2 or any one of claims 3 to 8 when appended to claim 2 wherein said flotation member is restrained from displacement relative to said flotation tank and said relative displacement between the floatation member and said liquid is effected by increasing the depth of said liquid in said floatation tank.

10. Apparatus as claimed in claim 2 or in any one of claims 3 to 8 when appended to claim 2 wherein the floatation member is displaceable relative to said floatation tank to effect relative displacement between the floatation member and said liquid.

11. Apparatus as claimed in any one of the previous claims wherein the force applicator is releasably secured to said first body.

12. Apparatus as claimed in claim 11 wherein the length of the force applicator between said first body and said floatation member is adjustable.

13. Apparatus as claimed in any one of the previous claims wherein first body comprises an elongate horizontal member.

14. Apparatus as claimed in claim 13 wherein said force applicator is longitudinally displaceable along said first body.

15. Apparatus as claimed in claim 2 or in any one of claims 3 to 14 when appended to claim 2 further comprising a base member on which the floatation tank is mounted with said first body rigidly secured to said base member.

16. Apparatus as claimed in claim 2 or in any one of claims 3 to 15 when appended to claim 2 in which said floatation tank is mounted on a fulcrum bar so as to be balanced thereon when said tank is empty.

17. Apparatus as claimed in claim 2 or in any one of claims 3 to 16 when appended to claim 2 comprising engagement means optionally and releasbly engageable between said tank and said floatation device to secure said tank to said device.

18. A method for applying a force to a body, comprising the steps of:

placing a floatation member within a floatation tank, providing said flotation tank with a known volume of liquid having a density greater than said floatation member, effecting relative displacement between said floatation device and said liquid to effect relative displacement of said floatation device into said liquid within said floatation tank to a position past an equilibrium position at which the member would normally float, to create an increase in upthrust created by mass of additional displaced liquid transmitting said increased upthrust to said first body by a force applicator rigidly extending between said first body and said floatation member.

19. A method as claimed in claim 18 for applying a measured force to said first body and further comprising the step of determining said force.

20. A method as claimed in claim 18 wherein said force is determined by mounting said tank on a force detecting means and measuring an increase in force exerted by said floatation tank during relative displacement of said member and said fluid past said equilibrium position.

21. A method as claimed in claim 19 wherein said force is determined by calculation by applying a known algorithm to measured physical values of the mass of the liquid, size of the tank and the height of the liquid within the tank to calculate said force.

22. A method as claimed in any one of claims 18 to 21 comprising the step of restraining said first body from displacement relative to said equilibrium position of said liquid at which said body would normally float.

23. A method as claimed in claim 22 comprising the step of increasing the volume of liquid within the floatation tank to increase the upthrust on said floatation member.

24. Stress testing equipment comprising apparatus for applying a force to a body as claimed in any one claims 1 to 17.

25. Display apparatus for demonstrating upthrust or buoyancy forces exerted on a floating member, comprising the apparatus as claimed in any one of claims 1 to 17.

26. Display apparatus as claimed in claim 25 for demonstrating Archimedes Principle.

27. Display apparatus as claimed in either claim 25 or claim 26 for demonstrating Newton's Third Law of Motion.

28. A system for storing potential energy comprising apparatus as claimed in any one of claims 1 to 17 wherein said first body is restrained from displacement relative to said equilibrium position of said floatation device.

29. A power source comprising a system for storing potential energy as claimed in claim 28.

0. An engine for converting potential energy into kinetic energy comprising a power source as claimed in claim 29.