Question

A tennis player receives a shot with the ball (0.060 0 kg) traveling horizontally at 56.0 m/s and returns the shot with the ball traveling horizontally at 34.5 m/s in the opposite direction. (Assume the initial direction of the ball is in the −x direction.)
(a) What is the impulse delivered to the ball by the racquet?
(b) What work does the racquet do on the ball?How many Joules?

Answer 1

Explanation:

It is given that,

Mass of the ball, m = 0.06 kg

Initial speed of the ball, u = 56 m/s

Final speed of the ball, v = -34.5 m/s (opposite direction)

(a) Let J is the impulse delivered to the ball by the racquet. It is equal to the change in momentum of the object as :

$J=m(v-u)$

$J=0.06\ kg(-34.5\ m/s-56\ m/s)$

J = -5.43 kg-m/s

(b) The work done by the racquet on thee ball is equal to the change in kinetic energy as :

$W=\dfrac{1}{2}m(v^2-u^2)$

$W=\dfrac{1}{2}\times 0.06((-34.5)^2-(56)^2)$

W = -58.372 Joules