How Is the Average Force Calculated in a Collision Problem?

[ballahboy]

A 3.0kg steel ball strikes a massive wall at 10m/s at an angle of 60degrees with the plane of thge wall. It bounces off with the same speed and angle. If the ball is in contact with the wall for .20s, wut is the average force exerted on the ball by the wall?

its is wut i got..
p=mv p=mv
3(10) =3(-10)
=30 =-30

deltaP=mvfinal-mvinitial
=30-(-30)
=60

averageF=deltaP/delta time
=60/.2
=300N
correct or incorrect?
can someone help me?

 

[ek]

Yep, looks good.

To be totally correct though, F*t is really impulse, not momentum, though they are the same magnitudes, so it really doesn't matter. But that's the kind of multiple choice question that can screw you over, so it's worth knowing.

 

[wais]

Your calculations for the change in momentum and average force appear to be correct. The average force exerted on the ball by the wall is 300N. This means that the wall exerts an average force of 300N on the ball during the 0.2 seconds of contact. It is important to note that this is an average force, as the force may vary throughout the contact time, but the overall average force is 300N.