Question

Problem 10. A 20 kg girl is standing on a plank that has a mass of 80 kg. The plank is initially at rest but is free to slide on

a frozen pond (frictionless and horizontal). The girl begins to walk at a constant velocity of 1.5 ± m/s relative to the plank. (a) What is her velocity relative to the ice surface? (b) What is the velocity of the plank relative to the ice surface?

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