exam 2 key - Question 21 Bens mass is 100 kg. He lands from...

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Question 21 Ben’s mass is 100 kg. He lands from a jump. His initial vertical velocity when his feet first touch the ground is 4 m/s downward. What is the average normal contact force that acts on Ben’s feet during this landing if he comes to a stop in 0.20 s? (3 pts) Given Answer: mass=100 kg (weight 981N) F– t = m(vf - vi) F (.20s)= (100kg)(0m/s--4m/s) F= 2000N + 981N (don’t forget to consider gravity, similar to the problem with the basketball player from the homework) F= 2981 N acting upward Question 22 Amy is in-line skating. She is rolling forward (north) on a flat section of road at 10 m/s. Her mass is 50 kg. The rolling friction acting on the wheels of her skates is 10 N backward (south). Air resistance creates a 15 N force also acting backward (south) on her. If these are the only horizontal forces acting on Amy, what is her horizontal acceleration as a result of these forces? (2 pts) Given Answer: Forces acting against Amy= 10 N from friction = 15 N air resistance
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This note was uploaded on 11/17/2011 for the course KNH 381 Lectur taught by Professor Walsh during the Summer '11 term at Miami University.

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exam 2 key - Question 21 Bens mass is 100 kg. He lands from...

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