Final answer:
The skier's change in velocity is 7.1 m/s.
Step-by-step explanation:
Given that a constant friction force of 21 N acts on a 71 kg skier for 24 s on level snow, we can find the skier's change in velocity using Newton's second law. The formula for force is F = ma, where F is the force, m is the mass, and a is the acceleration. Rearranging the formula to find acceleration, we have a = F/m. Substituting the given values, we get a = 21 N / 71 kg = 0.296 m/s². The change in velocity can be found using the formula v = u + at, where v is the final velocity, u is the initial velocity, a is the acceleration, and t is the time. Since the skier starts from rest, the initial velocity u is 0. Plugging in the values, we have v = 0 + (0.296 m/s²)(24 s) = 7.1 m/s. Therefore, the skier's change in velocity is 7.1 m/s.
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