Is it possible to use the potential energy of 2 rubber bands to make an object move? If so, how is the potential energy of the rubber bands used? And how can we explain this potential energy?? Please Register or Log in to view the hidden image!
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Well, the problem is that a rubber band doesn't really obey a nice potential function that I'm aware of. I recall being in a group trying to figure out some potential energy function for a rope of rubber bands, and they decidedly do not obey Hooke's law, and so honestly I have no idea. However, the Herbert Callen "Thermodynamics and an Introduction to Thermostatistics" 2nd edition has a somewhat extensive section on rubber bands from a thermodynamic viewpoint.
A rubber band sitting on a table, unstretched has no potential energy. A stretched rubber band does. Although the stretching of this bit of rubber may not obey Hooke's law (which simply states the relationship between stress and strain is linear) that doesn't matter here. The potential energy stored in the rubber band is simply the force times the distance. In the case of the rubber band, just like a spring, the force is not constant, and may not even be linear, so without going into calculus, you can imagine the force you apply while pulling the band from 100 mm to 101 mm may be 1 newton, and from 101 mm to 102 mm may be 1.01 newtons, you just multiply the length of stretch times the force and add them together. Energy is measured in force x distance. So in this case of the above: potential energy = (101-100) x 1.00 + (102-101) x 1.01 = 2.01 newton mm If you want the calculus, integrate the force over the differential length... but that doesn't mean much to some people and really isn't needed to understand the answer. Besides, I don't know how to write an integral equation on here very easily. lol Now you have stored up all this potential energy in the rubber band, and you'll notice the band is now taught and wants to contract back to its original length. If you used a rubber band for a slingshot for example, the band is released which allows a rock to accelerate and fly off towards a target. You've stored potential energy in the rubber band, you then released it, and imparted at least some of that energy to the rock. Thus you used the potential of the rubber band (or however many you want to use) to move the rock. You could also use it to rotate the axle on a toy automobile, or rotate the propeller of a toy airplane. In each case, you wind the rubber band which stores energy, and use that energy to move an object.
When you take one rubber band stretched between the middle finger, over the index finger and anchored by the thimb, one on each hand, and you release the tension, the stored energy, the potential energy, by releasing the thumbs then if the rubber bands strikes the butt of your boy friend and he moves, then yes, you have answered your own question in the affirmative: The potential energy in two rubber bands can indeed make objects move. Geistkiesel
