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The problem: A person in an apartment building 1 throws a ball horizontally at a

ID: 1956732 • Letter: T

Question

The problem: A person in an apartment building 1 throws a ball horizontally at a speed of 8 m/s out of a window toward his friend in a nearby apartment building that stands 18 meters away. The location of the window from which the ball is thrown is 50 m above ground level and the center of the window his friend is standing in is 22 m above street level. The entire height of the window to which the ball is thrown is 1.5 m.

Questions:

a) What is the amount of time it takes the ball to reach the second apartment building?

Explanation / Answer

No initial velocity in y-direction and no acceleration in the x-direction.
Hence the time taken to reach the second building is horizontal distance/horizontal speed = 18/8 = 2.25 sec.
Height lost in 2.25 sec, assuming g=10m/s^2 is (S=vt-(gt^2)/2), where v is initial vertical speed =0.

S = 0.5*10*2.25*2.25 = 25.3 m

Distance from the ground, where the second ball hits = 50-25.3 = 24.7 m

Center of Window height = 22m

Top of the window is 22+0.75 = 22.75 m

Hence the ball strikes the second building just above the window at a distance of 2.7m from the center of the window