Calculating Average Acceleration of 52g Super Ball

[nbroyle1]

A 52.0-g Super Ball traveling at 28.0 m/s bounces off a brick wall and rebounds at 16.5 m/s. A high-speed camera records this event. If the ball is in contact with the wall for 3.60 ms, what is the magnitude of the average acceleration of the ball during this time interval?

Im not really sure what formula to use for this problem. I don't think the mass of the ball is relevant to the average acceleration but not sure. I know average acceleration is
v(final)-v(initial)/t(final)-t(initial)

 

[Doc Al]

I know average acceleration is
v(final)-v(initial)/t(final)-t(initial)

That's the one you need. Hint: Velocity is a vector, so direction--and signs--matter.

 

[nbroyle1]

ok i tried plugging into the equation is this correct 16.5-28/.0036? I converted the miliseconds to seconds for the denominator.

 

[Doc Al]

ok i tried plugging into the equation is this correct 16.5-28/.0036?

No. You made an error with signs. If the initial velocity is +28 m/s, what is the final velocity after the rebound?

I converted the miliseconds to seconds for the denominator.

Good.

 

[nbroyle1]

Oh gotcha! ok thanks!