Question

If a person with mass 70.0kg, standing still, throws an object with mass 5.0 kg at 50.0 m/s, what will be the recoil velocity of the person, assuming he is standing on a frictionless surface?

A.) -3.6 m/s

B.) 0 m/s

C.) 3.6 m/s

D.) 50.0 m/s

Answer 1

Here we will conserve momentum,

Initial momentum will be zero, since both the person and object are at rest before throwing

Final momentum = (70*v) + (5*50) kg.m/s [ where v is recoil velocity of person ]

Conserving momentum,

Initial momentum = Final momentum

0 = 70v + 250

v = - 250/70 m/s

v = - 3.6 m/s