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 12.0 feet above the ground, and all three objects hit the ground just 0.800 feet away from the base of the house at the same time, 0.863 seconds after they are dropped. The rock hits with a thud and stays put, but the other two objects bounce. After another 0.647 seconds, the tennis ball reaches a maximum height of 6.75 feet, while the golf ball is 9.45 feet off the ground and still rising. Both have travelled an additional 0.600 feet horizontally. Calculate the magnitude of the average velocity of each object during these 1.51 seconds. Which object has the largest instantaneous velocity at the end of this time period?

Explanation / Answer

here,

height of window from ground, h = 12 ft

distance to hit from house, d = 0.8 ft

time to reach ground, t = 0.863s

time to reach max height, th = 0.647 s

Net time of journey, t = 0.647 + 0.863 = 1.51 s

Ht max height for tennis ball = 6.75 ft
Hg , max height for golf ball = 9.45 ft

additional distance to wall, d = 0.600 ft

net horizontal distance for golf and tennis ball, x = 0.6 + 0.8 = 1.4 m

Average Speed, Savg = Total Distance travelled/total time taken

For Rock,
Savg = 12 / 0.863
Savg = 13.905 ft/s

for Golf ball,
Savg = total distance travelled/ total time,t
Savg = (12 + 9.45)/(1.51)
Savg = 14.205 ft/s

For Tennis ball,
Savg = total distance travelled/ total time,t
Savg = (12 + 6.75)/(1.51)
Savg = 12.417 ft/s

instantaneous velocity is simply velocity at a point in path, as all three object have same mass and same release height, but golf ball attain more height than tennis ball , therefore GOLF BALL has maximum instantaneous velocity.

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