# Homework Help: Average Force Applied by Catcher

1. Nov 4, 2007

### Jtappan

1. The problem statement, all variables and given/known data

0.15 kg baseball is pitched with a speed of 36 m/s (79.2 mph). When the ball hits the catcher's glove, the glove moves back by 4.9 cm (1.96 in.) as it stops the ball.
(a) What was the change in momentum of the baseball?
5.4 kg·m/s opposite the ball's direction of motion
(b) What impulse was applied to the baseball?
5.4 kg·m/s opposite the ball's direciton of motion
(c) Assuming a constant acceleration of the ball, what was the average force applied by the catcher's glove?
Magnitude _____ kN opposite the ball's direction of motion

2. Relevant equations

??????

3. The attempt at a solution

i got everything except the magnatude of the force applied by the glove... i dont know how to do this when i have to relate distance to this problem.

2. Nov 4, 2007

### Staff: Mentor

Use the distance and speed to figure out how much time it took for the catcher to stop the ball.

3. Nov 4, 2007

### Jtappan

i keep doing this problem and it does not work out. I dont know what im doing wrong. for the time i get .13637.

4. Nov 4, 2007

### Staff: Mentor

That's quite a bit off. Show how you did the calculation. Also realize that the speed is not constant during the catch--you'll need to use the average speed.

5. Nov 4, 2007

### Jtappan

ok i did it again and got .2722222 s for the time. just did xf-xi = .5(vf+vi)t

6. Nov 4, 2007

### Staff: Mentor

Don't forget to use distance in meters, not cm.

7. Nov 4, 2007

### Jtappan

.002722222 is the time??

giving force as .00001469988?

8. Nov 4, 2007

### Staff: Mentor

Good.

No. How did you get that?

9. Nov 4, 2007

### Jtappan

f(deltaT) = mv-mvi

did i plug it in wrong?

10. Nov 4, 2007

### Jtappan

never mind i got it thank you for your help