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Unformatted text preview: PHY-7A Review for Midterm 2 Problem 1. A bouncy ball is placed on top of a basket ball and both are dropped from some height h . After they hit the ground, the bouncy ball flies into the air to a spectacular height! What is the maximum height H reached by the bouncy ball? Assume that the mass m of the bouncy ball is much smaller than the mass M of the basket ball so that m/M ≈ 0. Assume further that all collisions are perfectly elastic. Ignore the radius of the basket ball and neglect any effects of air resistance. Is your answer an over- or under- estimate for the height H ? Justify your claim in terms of the assumptions listed in the problem statement. M h m Problem 2. Your GSI is driving 25 mi/hr (40 km/hr) down a hill with a 10 ◦ grade. Without warning, a pedestrian steps into the road and begins to cross the street just 33 ft (10 m) in front of her. She slams on her brakes, but she’s not sure she can stop in time! Does this story end in tragedy? The coefficients of static and kinetic friction for tires on asphalt are μ s = 1.6 and μ k = 0.9, respectively. Assume that your GSI’s car weighs 2800 lbs (1300 kg). What would happen if this same event took place on a rainy day? What would happen if your GSI had been driving a 5400 lbs (2400 kg) pick-up truck?your GSI had been driving a 5400 lbs (2400 kg) pick-up truck?...
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This test prep was uploaded on 04/03/2008 for the course PHYSICS 7A taught by Professor Lanzara during the Spring '08 term at Berkeley.
- Spring '08