Calculating Force Needed to Accelerate a 7.00g Pellet from Rest to 175 m/s

[airelemental135]

8. What average force is needed to accelerate a 7.00-gram pellet from rest to 175 m/s over a distance of 0.700 m along the barrel of a rifle?

9. A fisherman yanks a fish out of the water with an acceleration of 4.5 m/s^2 using very light fishing line that has a "test" value of 22 N. The fisherman unfortunately loses the fish as the line snaps. What can you say about the mass of the fish?

10. A 0.140-kg baseball traveling 45.0 m/s strikes the catcher's mitt, which, in bringing the ball to rest, recoils backward 11.0 cm. What was the average force applied by the ball on the glove?3

I tried doing number 8 on my own.

vfinal^2=vinitial^2 + 2ad
175m/s=0^2 + 2a(0.700m)
a= 125m/s
F=ma
F=(7.00g)(125 m/s)
F=875N

Is this correct>? How do you do the others?

 

[whozum]

You did 8 correct all the way to the last part, since you use MKS units, you need the mass in kilograms, 7 grams = 0.007kg.

Draw a force diagram for 9, should be all you need. Assume he pulsl the fish straight up

10 is done the same way as 8