Quiz%204%20Feb%2018%20%28Ch%204%29%20w%20sol

# Quiz%204%20Feb%2018%20%28Ch%204%29%20w%20sol - v y is zero...

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Student name________________________________________ Student NID__________________________________________ PHY 2053C_0001 Quiz, Feb. 18, 2011 1) On his little planet, Little Prince stamps on the ground and finds himself moving directly upwards with an initial velocity v 0 = 5 m/s. He returns back on the ground in 4.0 s. His mass is only 32 kg. Find Little Prince’s weight (in pounds) on his planet. Ignore the planet’s curvature, any air resistance, and the distance dependence of gravitation. 1 lb = 4.448 N, and 1 N = 1 kg × m/s 2 Let the gravitation on that planet be g p . We can consider the upward motion, which will take half of total time, t 1/2 = 2.0 s. Also, at the top the velocity
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Unformatted text preview: v y is zero, so y p 1/ 2 2 p 1/ 2 v v g t v 5.0m / s g 2.5m / s t 2.0s = =--= = =-The weight on the planet is: ( 29 ( 29 2 p m w mg 32kg 2.5 80N s = = = The weight in lb is: ( 29 1lb w 80N 18lb 4.448N = = 1) A 2180 kg car is traveling with a speed of 12.0 m/s along a horizontal straight line. What is the magnitude of the horizontal net force that is required to bring the car to a halt in a distance of 40.0 m? We can find the force from: F ma = We need to determine the acceleration, a, and then F: ( 29 ( 29 2 2 f 2 2 2 v v 2ax v a 2x 2180kg 12m / s mv F 3924N 2x 2 40m = = +-= = -= -= -×...
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