# Answer to Question #13258 in Mechanics | Relativity for hanusha

Question #13258

A bullet moving with a speed of 200m/s strikes abag of sand & remains in it. the masses of bag& bullet are 4.5kg&500g respectively. If the sand bag is free to move its speed is

Expert's answer

Let I be the momentum of the bullet and J be the momentum of a bag striked with it, M and m be mass of the bag and the bullet respectively, V and W velocities of the bullet and the striked bag. Then:

I = mV

J = (M+m)W

I = J

mV = (M+m)W

W = mV/(M+m)

W = 0.5*200/(4.5+0.5) = 20 m/s.

So, the bag's speed is 20 m/s.

I = mV

J = (M+m)W

I = J

mV = (M+m)W

W = mV/(M+m)

W = 0.5*200/(4.5+0.5) = 20 m/s.

So, the bag's speed is 20 m/s.

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