# physics repost

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A marksman at rest fires a 4.00-kg gun that expels a bullet of mass 0.0140 kg with a velocity of 181 m/s. The marksman's mass is 81.0 kg. What is the marksman's velocity after firing the gun?

mc = 85kg
md = 0.0140

-(0.0140)(-181)/85
= .0298 m/s

• physics repost -

Wouldn't it be

massbullet*velocitybullet=massmarksman*v

v then would be something different than your calcs.

• physics repost -

I guess its not suppose to be there. I got it somehow though. I don't know what to do now

• physics repost -

solve for v.

v= massbullet/massmarksman * velocty bullet.

Algebra.

my answer for this one was correct its not 0.0312

• physics repost -

Yes, your answer was correct. You were right to add the mass of gun and marksman, since they move together. This assumes the ground he is standing on exerts no horizontal force, which is not strictly true after the shot is fired

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