A man on a motionless raft jumps from the raft with a speed of 3 ft/s with respe

Question

A man on a motionless raft jumps from the raft with a speed of 3 ft/s with respect to the raft. If the man weighs 150 lb and the raft 400 lb, what arc their final velocities with respect to the water? In the preceding problem, let's say there are two 150 lb men on the raft, and they both jump with a speed of 3 ft/s with respect to the raft. Will the final velocity of the raft be greater if the two jump together or if they jump one after the other? Two blocks of 2 and 3 kg mass are moving toward each other at the speeds of 6 and 10 m/s respectively. They hit with a coefficient of restitution of 0.4. What are their final velocities?

Explanation / Answer

(6) Initial momentum =0
Let us consider that
Final velocity of man is Vm and that of raft is VR
Final momentum = 150Vm + 400VR
it is given that Vm - VR = 3
Vm = VR + 3
applying conservation of momentum
initial = final
150Vm + 400VR = 0
150 (VR + 3) + 400 VR = 0
550 VR = -450
VR = -0.818 ft/s
Now velocity of men
Vm = -0.818 + 3 = 2.18 ft/s

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