Question

5))A 40 kg ice skater is gliding along the ice, heading due north at 4.4 m/s. The ice has a small coefficient of static friction, to prevent the skater from slipping sideways, but µk = 0. Suddenly, a wind from the northeast exerts a force of 4.0 N on the skater. (a) Use work and energy to find the skater's speed after gliding 90 m in this wind. m/s (b) What is the minimum value of µs that allows her to continue moving straight north?

Answer 1

Force along south to skater

F = 4 sin 45 = 2.828

using work energy theorem

2.828* 90 = 0.5* 40 * ( 4.4^2 - v^2)

v = 4.253 m/s

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b)

fricitonal force along east must be

F = 4 cos 45

u * 40* 9.8 = 4 coa 45

u = 0.007

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