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283Matter is something that is made up of atoms which are linked together to form larger compounds called molecules Some molecules are made by joining together the repeated subunits of atoms Such molecules are called polymers In some polymers the subunits are identical Rubber is a natural polymer and has chains of molecules giving it its natural elasticity A natural polymer with elastic properties like this is called an elastomer The molecular chains of an elastomer act like springs giving it the bouncing property A rubber ball features a hollow rubber sphere filled with air or some other suitable gas for the sport The gas consists of relatively unorganized molecules which just acquire the space it is provided When the ball bounces on the floor force is exerted upwards contracting the gas inside When a rubber ball bounces its structure is deformed inwards Due to the elastic nature of the ball the deformation reverts back causing an upward force thus resulting in the bounce of the ball
When the temperature increases the gas molecules inside the tennis ball expand As the molecules expand their energy increases as they bounce around more erratically This increased energy and movement results in a higher bounce On the other hand a temperature decrease causes the gas molecules to contract and move around more sluggishly As a result a cooler ball has a much lower bounce Coefficient of restitution Coefficient of restitution e is the ratio of the final to the initial relative velocity between two objects after they collide It is a value indicating the remaining kinetic energy left in the object after the collision The speed of the ball after bouncing from the floor is always less than the impact speed due to energy losses occurring due to the deformation of the ball Temperature always affects the coefficient of restitution as the stiffness of the ball changes thus affecting the bounce of the ball Thus the coefficient of restitution that is being investigated here will show the relationship of the effect of temperature Coefficient of restitution lies between 0 to 1 where 1 is a perfectly elastic collision which means that no energy is lost and 0 means that the collision is perfectly inelastic When e 0 Perfectly inelastic The object does not bounce back at all in this case as all of the kinetic energy is converted to heat or work done during deforming the objects and is thus lost When 0  e 1 This is a real world inelastic collision in which some kinetic energy is dissipated The object bounces back but not perfectly as there is still some energy that is dissipated When e 1 This is a perfectly elastic collision in which no kinetic energy is dissipated and the objects rebound from one another with the same speed and height with which it fell In this case the ball will bounce perfectly to the same height as the drop height In situations where the frictional force can be neglected and when the object is dropped from rest to a horizontal surface the total energy is the potential energy Ep of the object and the comparison is done between the PE at bounce height and PE at drop height The change in the kinetic energy Ek here is zero thus giving us the equation