Question

A bullet of mass 7 g is fired into a block of metal weighing 7 kg. the block is free to move. after the impact the velocity of bullet and block is 70m/s. find the initial velocity of bullet.

Answer 1

m1 = 7/1000 kg 
v1  = ?
m2 = 7kg
V2 = 70 m / s 
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According to the linear momentum law 
m1v1 = m2v2
7/1000 v1 = 7 x 70 
v1/1000    = 10 
v1             = 10000 m/s 
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