Question

A tennis player player receives a shot with the ball (.06kg) travelling horizontally at 50.0 m/s and returns the shot with the ball travelling horizontally at 40.0 m/s in the opposite direction. a) What is the impulse delivered to the ball by the tennis racquet? b) What work does the racquet do on the ball?

Answer 1

Eeek! I don't know...I'm not good with formulas and stuff, good luck though! :D

Answer 2

Impulse is change in momentum = final - initial

So, initial momentum is = mv = 0.06 x 50 = 3 J m/sec
final momentum = mv' = 0.06 x (-40) = -2.4J m/sec ...{the velocity is taken '-ve' due to change in direction.

so impulse 'J' = 3 - (-2.4) = 5.4 J m/sec

Answer 3

Is there any work done? I know that Work is the Force vector times displacement and the sum of forces is the derivative of momentum. the change in momentum/time is also the sum of forces.

Answer 4

But what would be the displacement?

Answer 5

W.D. = change in kinetic energy = final - initial

KE. = (1/2)mV^2

Answer 6

Work-Kinetic Energy Theorem?

Answer 7

Exactly.

Answer 8

What velocity do I use then?

Answer 9

you have both velocities stated - final and initial both.

Answer 10

I know the squared will keep the answer positive.

Answer 11

Ok...

Answer 12

Yes right.

Answer 13

I think 40 because it's the return shot and that return shot is the one in which the racket strikes the ball.

Answer 14

@apoorvk Would I use 40m/s as my velocity?

Answer 15

final will be 40, initial will be 50.

Answer 16

so find out initial and final kinetic energies, and then calculate the change.

Answer 17

@apoorvk
-27 Joules?

Answer 18

With Modulus!