A man with a mass of 69 kg skis down a frictionless hill that is h = 3.9 m high.

Question

A man with a mass of 69 kg skis down a frictionless hill that is h = 3.9 m high. At the bottom of the hill the terrain levels out. As the man reaches the horizontal section, he grabs a 20-kg backpack and skis off a 2.0-m-high ledge.

1. What is the speed of the skier just before grabbing the back pack? (3 points)

2. What is the speed of the skier just after grabbing 20-kg back pack? (3 points)

3. At what horizontal distance from the edge of the ledge does the skier land? (5 points)

    (Assume there is no air resistance)

Explanation / Answer

using conservation of energy, mgh = .5*m*v^2
so, v=sqrt(2gh)= 8.74 m/s     <----------ans(1)

conserving momentum,we get:

69*8.74 = 89*v'

so, v' = 6.78 m/s      <--------ans(2)

using the relation, s=.5*9.8*t^2

we get, t= .64s

so distance covered = t*v' = 4.33m    <-------ans(3)

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