1. A student wearing frictionless in-line skates on a horizontal surface is pushed by a friend(adsbygoogle = window.adsbygoogle || []).push({});

with a constant force of 47 N. How far must the student be pushed, start-

ing from rest, so that her final kinetic energy is 354 J ?

Answer in units of m.

for this i did 354/2 which i got 177 then i divided by 47 . is that correct?

2 (part 1 of 2) A 4.78 g bullet moving at 510.8 m/s penetrates a tree trunk to a depth of 4.93 cm. a) Use work and energy considerations to find the magnitude of the force that stops the bullet.

Answer in units of N.

for this i did KE=1/2mv^2 and i found the answer and did f=ma. is that right??

3. (part 2 of 2) b) Assuming that the frictional force is constant, determine how much time elapses between the moment the bullet enters the tree and the moment the bullets stops moving.

Answer in units of s.

for this one i just did vf^2=vi^2+2at. is that correct??

THANK YOU!!

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# Homework Help: Basic momentum and magnitude questions!

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