What is the average force exerted by the ball on the wall

[Chrisleo13]

A 425 g ball with a speed v of 6.5 m/s strikes a wall at an angle of 30° and then rebounds with the same speed and angle. It is in contact with the wall for 9.0ms. (a) What is the impulse on the ball (take positive as down in the figure)?


b. What is the average force exerted by the ball on the wall (take positive as down in the figure)?


hmmm, I think i had it. I used

vi = v cos θˆi − v sin θˆj
vf = v cos θˆi +v sin θˆj

J = mvf − mvi

But I am still getting it wrong. Any help is helpful. Thanks

 

[christensen]

find the acceleration vector from the inital and final velocity vectors and the change in time.

Plug that into F = ma

you now have the force.

Solve for Impulse using the same method.

 

[Chrisleo13]

vf - vi / t = a


I did that and didn't get it right when I plugged it into F= ma.

 

[christensen]

you want to break the vector velocities into components