Laws of Motion

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Question : 19
Total: 40
A shell of mass 0.020 kg is fired by a gun of mass 100 kg . If the muzelespeed of the shell is 80 m s1, what is the recoil speed of the gun?
Solution:  
Here, mass of the shell, m1=0.02 kg; mass of the gun, m2=100 kg Initial velocities of both the shell and the gun are zero i.e. u1=u2=0 After firing, speed of the shell, v1=80 m s1
Let v2 be the recoil speed of the gun. According to the principle of conservation of momentum,
m1v1+m2v2=m1u2+m2u2
0.02×80+100v2
=0.02×0+100×0 or v2=
0.02×80
100
=0.016 ms1
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