Physics question about mass?

Question

Four 50 kg girls simultaneously dive horizontally at 2.5 m/s from the same side of a boat, whose recoil velocity is 0.1 m/s. What is the mass of the boat?

Anybody know?

Answer 1

Newton's third law applies here and to work out the mass do as below:

From conservation of momentum:
Initial momentum=Final momentum
momentum = mass*Velocity
(4*50)*2.5=0.1*mass of boat
mass of boat= (4*50*2.5)/0.1 = 5000

so the mass of thr boat= 5000kg

Answer 2

Yes, I know. And if you understood Newtons 3'rd law and conservation of momentum, so would you ☺

4*50*2.5 = .1x

so the boat has a mass of 5,000 kg.

HTH

Doug