Question

anita is bouncing a tennis ball on the sidewalk. she drops the ball and then watches it bounce back up. at which point does anitas tennis ball have the most kinetic energy?
o as it begins to fall to the sidewalk
o as it hits the sidewalks surface
o just after it hits the sidewalks surface
o just as it reaches the top of the bounce

Explanation:

Kinetic energy (\(KE\)) is related to motion, \(KE = \frac{1}{2}mv^2\) (where \(m\) is mass, \(v\) is velocity). At the top of the bounce, the ball’s vertical velocity is 0 (momentarily at rest before falling again). When it begins to fall, it has velocity (so \(KE>0\)). When hitting or just after hitting the sidewalk, it’s moving (so \(KE>0\)). Only at the top of the bounce, \(v = 0\), so \(KE = 0\).

Answer:

just as it reaches the top of the bounce