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## Homework Statement

An archer fires a 20g bolt with a speed of105 m/s through a 400 g apple initially at rest.

The bolt exits the apple with a speed of 45 m/s. What is the percent change in kinetic energy of the apple/bullet system?

m1= 20g

Vi1= 105 m/s

Vf2= 45 m/s

m2= 400g

Vi2= 0 m/s

Vf2= ?

## Homework Equations

(m1v2+m2v2)i=(m1v2+m2v2)f

ΔKE= ((.5)(m1)(Vi1)

^{2}+(.5)(m2)(Vi2)

^{2})i -((.5)(m1)(Vf1)

^{2}+(.5)(m2)(Vf2)

^{2})f

%ΔKE= 100(F-I/I)

## The Attempt at a Solution

(20g)(105 m/s)+(400g)(0 m/s)=(20g)(45 m/s)+ (400g)(vf)

2100(g)(m/s)=900(g)(m/s)+(400g)(vf)

1200g(g)(m/s)=400g(vf)

3 m/s = vf

ΔKE= ((.5)(20g)(105m/s)

^{2}+(.5)(400g)(0)

^{2})i -((.5)(20g)(45m/s)

^{2}+(.5)(400g)(3 m/s)

^{2})f

22050J-110250J=-88200J

100x(-88200)/110250J= -80%

Figured it out myself. :)

:::::Lashawnda:::::

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