A tennis ball is dropped on a horizontal smooth surface. It bounces back to its original position after hitting the surface. The force on the ball during the collision is proportional to the length of compression of the ball. Which one of the following sketches describes the variation of its kinetic energy K with t time most appropriately? The figures are only illustrative and not to the scale.

Step-by-step solution

When ball of mass ' m ' dropped from height and strikes to ground.It's kinetic energy is converting into elastic potential energy due to compression. So after time ' t ' its final velocity, v = u + at u is initial velocity of ball, a is acceleration of ball and t is time. ⇒ v = 0 + - g t v = - gt Negative sign shows downward direction. Now kinetic energy of ball, K . E . = 1 2 mv 2 = 1 2 m - gt 2 ⇒ K . E . = 1 2 mg 2 t 2 ⇒ K . E . ∝ t 2 So, it is upward parabola. But after comple