Test_3_B - PHYS 2425 - Dr. Honan - Test 3 - B Possibly...

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Name _________________ Possibly Useful Information: g = 9.80m/s 2 Problem 1 (2 points each) A crazed physicist risks his life rotating on a frictionless stool. When he pulls his arms in he spins faster. Give the signs of the changes in kinetic energy, angular momentum and angular velocity. Answer +, - or 0. ______ [i] Δ K ______ [ii] Δ L ______ [iii] Δ ω Problem 2 A 3kg mass is at (3m,-4m), a 5kg mass is at (0,4m) and a 2kg mass is at (-2m,0). (6 points each) (a) What are the coordinates of the center of mass? (b) What is the moment of inertia for rotations about the y -axis? Problem 3 (a) A 200 g glider moves at 0.3 m/s on an air track toward a 300 g glider moving in the opposite direction at 0.1 m/s. If the collision is elastic then what are both final velocities? (8 points) (b) Before being hit by a bat, a 0.15kg baseball has a velocity of 40,0 m/s . It leaves the bat with velocity 45,25 m/s . If the bat is in contact with the ball for 0.05s then what is the average force of the bat on the ball? (7 points)
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Test_3_B - PHYS 2425 - Dr. Honan - Test 3 - B Possibly...

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