# Momentum + Walking On a Boat

1. Oct 14, 2012

### spooky655

A 200 kg canoe lies at rest in the water, near a dock but untethered. Any
friction between the canoe and the water is negligible. A 60 kg man runs along the
dock toward the boat and jumps in, at velocity v = 5 m/s (directed toward the long
dimension of the canoe). The coeﬃcient of friction between his shoes and the boat
ﬂoor is µk = 0.3, µs = 0.5; he slides along the boat ﬂoor and comes to rest relative to
the boat. His 70 kg friend does the same thing, jumping with v = 8 km/s, and with
µk = 0.1, µs = 0.8 (he has diﬀerent shoes). After they come to a stop in the boat, a
third person with m = 80kg, who was at the opposite end of the boat, begins to walk
toward them, at v = 2km/s relative to the ground. What is the speed of the boat
(relative to the ground) at this time, when the two jumpers are at rest relative to the
boat, and the third person has begun walking?

Is friction relevant? How do you calculate the final speed?

2. Oct 15, 2012

### haruspex

If this is a homework question, there's another forum for that. Anyway, you should present your own attempt at a solution.
I believe momentum will be conserved.