a bullet of mass 20g is horizontally fired with a velocity of 150m/s frm a pistol of mass 2kg. What is the recoil velocity of the pistol?

For this question we will use consevasion of momentum -

m1v1 +m2v2 = m1u1 + m2u2

m1 = 20g = 0.020 kg = 20/1000 kg

u1 = 0m/s

v1 =  150m/s

m2 = 2 kg

u2 = 0m/s

v2 = unknown = v

= [ 20/1000 * 150 ] + [ 2v ] = [ 20/1000*0] + [ 2 * 0 ]

= 3 + 2v = 0

= 2v = -3

= v = -3/2

= v = -1.5m/s

ANS ---- recoil velocity of the pistol is -1.5m/s 

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