The coefficient of restitution is velocity dependent. In a spherical cow theory (the canonical example of an overly simplified physics model), yes. Theoretically, shouldn't the ball have the same bounce efficiency no matter the height? The ball would bounce about the same height for those large drop heights. If you were dropping the ball from 100 meters vs a kilometer, drag would be a big effect. Since drag is proportional to the velocity squared, it's a small effect. At the bottom of your 200 cm drop, the ball is going a bit over 1/5 of terminal velocity. The terminal velocity of a tennis ball is about 30 m/s. There's a small effect for these smallish velocities, but that's probably not what you're seeing. Is it something to do with air resistance? In the case of a tennis ball, remember that a long drop creates moreĪirspeed-related losses than a short one there's more than reboundĮnergy efficiency involved in that experimental setup. One way of determining the hardness of steel is to bounce a hardenedīall against a sample: the hardest steel does the least energy-absorbingĭeformation, so returns the ball higher than softer metal. Make good toys, but are excellent for sound-deadening. A fast impact would imply a high strain rate,īut the rebound may be slow by comparison. Materials (which have different mechanical constants at different When a low-velocity impact makes a small dent.Īlso, some ball structures may include viscous or viscoelastic If it is deformed to a near-hemisphere, though be very lively The efficiency of the bounce depends on how greatly the ball isĭeformed a thick rubber ball may lose more energy to internal heating It then is forced upward by the springiness of the When a ball bounces, it is deformed at the contact point to becomeĪ compressed spring, having almost all of the kinetic energyĬonverted to spring compression, as the velocity downward goes
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