Young Jeffrey is bored, and decides to throw some things out of the window for f

Question

Young Jeffrey is bored, and decides to throw some things out of the window for fun. But since he is also very curious, he decides to do so in a controlled way. Jeffrey takes a rock, his tennis ball, and one of his father's golf balls and sets them on the sill of an open window. Then he uses a flat board to carefully push them all out of the window at the same time. The 2nd story window is 14.0 feet above the ground, and all three objects hit the ground just 0.350 feet away from the base of the house at the same time, 0.933 seconds after they're dropped.

The rock hits with a thud and stays put, but the other two objects bounce. After another 0.699 seconds, the tennis ball reaches a maximum height of 7.88 feet, while the golf ball is 11.0 feet off the ground and still rising. Both have travelled an additional 0.263 feet horizontally.

Calculate the magnitude of the average velocity of the golf ball during these 1.63 seconds.

Explanation / Answer

stones final vertical displacement relative to earth surface= 11ft =11 i

stones final horizontal displacement relative to earth surface= 0.35 + 0.263 =0.613 ft = 0.613 j

stones initial displacement relative to earth surface=14ft = 14 i

stones initial displacement relative to earth surface=0

average velocity= total displacement/ total time = (14-11)i +(0.613-0) j/1.63

average velocity magnitude= sqrt(32 + 0.6132) / 1.63 =1.878 fts-1

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