Question

A tennis ball is hit into the air with a racket. When is the ball’s kinetic energy the greatest? Ignore air resistance.

A.
when it leaves the racket
B.
just before it reaches the ground
C.
when it reaches its maximum height
D.
when its kinetic energy and potential energy are equal
E.
just before it starts falling downward

Answer 1

Answer B is the correct answer

We know that kinetic energy
`E = (1)/(2) mv^2`, where m is the mass of object and v is the velocity of object.

In this case only velocity is the variable, mass remains constant.

So point having higher velocity has higher kinetic energy.

When it leaves the racket, the ball will be having a certain height, but just before it reaches the ground it will not having any height. So maximum velocity of ball is at that time when it reaches just above the ground.

So option B is the correct answer.