- #1

dani123

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- 0

## Homework Statement

A 30.0-kg gun is standing on a frictionless surface. The gun fires a 50.0-g bullet with a muzzle velocity of 310 m/s.

a) calculate the momenta of the bullet and the gun after the fun was fired.

b) calculate the kinetic energy of both the bullet and the gun just after firing.

## Homework Equations

Mgun*Vgun + Mbullet*Vbullet= 0 before firing

KE= 1/2 M*V^2

## The Attempt at a Solution

a) Before the firing, the system is at rest and therefore the momentum is ZERO. After firing, the total momentum is still ZERO. There is no net momentum gained or lost in this system. ----> Here, I am just looking if anyone could let me know if my reasoning is correct, and I was also wondering if there are anything else I should show in order to get full mark value?

b) After firing

0= (30 kg) Vgun+ (0.05kg) (310 m/s)

Vgun=[(0.05kg)(310m/s)]/(30kg) = 0.517m/s

Ke=1/2 M*V^2

for bullet after firing: KE= 1/2 (0.05kg)(310m/s)^2=2402.5J= 2.40x10^3J

for the gun after firing: KE=1/2 (30kg)(0.517m/s)^2=4.01J

Also here, I am just looking for someone to check that I did this problem correctly and also to check that the SIGNIFICANT FIGURES are correct. Thank you so much in advance.

b)