A boy throws a ball straight up into the air so that it leaves his hand at 11 m/
ID: 1771682 • Letter: A
Question
A boy throws a ball straight up into the air so that it leaves his hand at 11 m/s. If the ball has mass 0.15 kg and the boy's arm moved through 1.5 m as he threw the ball, then what average force did he exert on the ball? #2) Three equal masses are suspended from a frictionless, massless pulley system, as shown. Once the system has reached equilibrium, what angles will the strings make with respect to the horizontal? #3)A fuzzy die (m = 0.2 kg) hangs from the ceiling of a car. When the car accelerates forward along a horizontal road, the die swings backward so the the string supporting it makes an angle of 4o with the vertical. What is the acceleration of the car? HINT: We're not concerned about how the die swung back, only that it has swung back.
Explanation / Answer
1)
work done by force + work done by gravity = change in kinetic energy
F x 1.5 -mg (1.5) = 0.15x0.5x11x11
F = 7.52 N
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