![]() Is steel really more elastic than rubber?"Īdding to Nicael's and Dzuris' excellent answers, I thought it's worthwhile to go into greater detail about exactly why some elastic objects do not bounce in a place where rubber balls do. If there's sand instead of hard surface, any object falling in sand would behave like an object which falls on the hard surface and fails the 3rd stepĢ - See " Clarifying the actual definition of elasticity. If there's a trampoline instead of the floor and an object won't stick to it once it falls on it, it will bounce back. 2ġ - This answer is considering a system where the surface of the floor doesn't deform itself. It would certainly deform less than the rubber ball, but would still bounce pretty good. So, out of three objects, only the rubber ball will bounce.Īs an additional example, you could consider the third, steel ball (not drawing it here :). What about the third step? The plasticine ball fails it - its gained internal energy was mostly lost because of being transformed into thermal energy. Thus, the book is not a contender anymore. A book primarily fails to bounce because its shape favours other modes of energy propagation - dissipation via vibration. Now they will fall on the ground.īalls pass the second step, they deform to a different degree. Well, any of them can pass the first step since they have got the speed. Let's see consider three different objects - a rubber ball, a plasticine ball and a book, and see how they behave. In other words, the objects bounces, if there is deformation and it's elastic, not plastic or viscous and most of the elastic potential energy is realised into acceleration of the whole object in the opposite direction. In order to bounce, an object must "pass" all the steps above. Now it has its kinetic energy back, and thus has the speed to go up again. If all the above steps are passed, the object has to "un-deform" - internal energy gained because of deforming and not lost in the step 3 is turning back into the kinetic energy. no (or little) part of it is dissipated as heat, vibration, etc (guess there could be another form of dissipation.) there's no (or insignificant) loss in newly gained internal energy, i.e.the object deforms ( doesn't shatter, break, explode, catch fire, etc) and its kinetic energy transforms into the internal energy. ![]() object is going to touch the surface, having a kinetic energy $E$.In order for an object to bounce 1, the sequence of events would be following: Because bouncing requires the object to be elastic - shortly after it deforms, its shape should return to the one it had before deforming. ![]()
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