A man with a mass of 65 kg skis down a frictionless hill that is5.0m high. At th

Question

A man with a mass of 65 kg skis down a frictionless hill that is5.0m high. At the bottom of the hill the terrain levels out. As the man reaches the horizontal section, he grabs a 20-kgbackpack and skis off a 2.0m-high ledge. At what horizontaldistance from the edge of the ledge does the man land?
I understand that his velocity as he picks up the backpack is9.9 m/s but I don't know how to get how far he went.
I understand that his velocity as he picks up the backpack is9.9 m/s but I don't know how to get how far he went.

Explanation / Answer

When he grabs the backpack his speed is SQR(2x 9.8 x 5)=9.9m/s, so his momentum is 65 x 9.9=643.5kg.m/s, so after he grabs the backpack his momentumwill be the same and his speed will be 643.5/(65+20)=7.57m/s. It takes SQR(2s/a)=SQR 2 x 2/9.8)=0.64 sec tofall 2m, and in this time he will have travelled horizontally 0.64x 7.57=4.84 metres from the ledge.

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