Hi I need help
During a collision with a wall, the velocity of a 0.200-kg ball changes from 20.0 m/s toward the wall to 12.0 m/s away from the wall. If the time the ball was in contact with the wall was 60.0 ms, what was the magnitude of the average force applied to the ball?

Question

Hi I need help
During a collision with a wall, the velocity of a 0.200-kg ball changes from 20.0 m/s toward the wall to 12.0 m/s away from the wall. If the time the ball was in contact with the wall was 60.0 ms, what was the magnitude of the average force applied to the ball?

matt101 · Answer

We'll get the force from F=ma. We already have the mass, so what we need to figure out is the acceleration.

We have an initial velocity (20 m/s), a final velocity (-12 m/s), and a time interval (0.06 s). This means we can use the following equation:

$$a=\left| \frac{ v_f-v_i }{ t } \right|$$$$a=\left| \frac{-12-20 }{ 0.06 } \right|$$$$a=533$$

I'm taking the absolute value since we only care about the magnitude of the force. We have the acceleration, so just plug it into the force equation:

$$F=ma$$$$F=0.2 \times 533$$$$F=107$$
The average force applied to the ball is 107 N.

anonymous · Answer

OK great thank you. I didn't think we could have used kinematics