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## Homework Statement

A rifle with a barrel length of 56 cm fires a 10 g bullet with a horizontal speed of 350 m/s. The bullet strikes a block of wood locked in position and penetrates to a depth of 13 cm.

What resistive force (assumed to be constant) does the wood exert on the bullet?

How long does it take the bullet to come to rest?

## Homework Equations

f = m * a

d = v * t

vf = vi + a * t

## The Attempt at a Solution

Force of wood on bullet = 4700 (was confirmed correct)

f = m * a

a = -471154 N

How long does it take the bullet to come to rest?

I tried

D = v * t1 for the barrel

.55 = 350 * t1

t1 = 350 / .55 = .0016 seconds

For the wood

vf = vi + a * t2

0 = 350 - 471154 t2

t2 = 350 / 471154 = .000743 seconds

t1 + t2 = .002343 seconds which is wrong.