A ball thrown horizontally from a point 15 meters above the ground with initial
ID: 1882019 • Letter: A
Question
A ball thrown horizontally from a point 15 meters above the ground with initial horizontal speed of 29 m/s. How far will it travel horizontally before it hits the ground? (use g = 10 m/s2; round your answer to two decimals).
A ball thrown horizontally from a point 39 meters above the ground, strikes the ground after traveling horizontally a distance of 12 meters. With what speed was it thrown? (use g = 10 m/s2; round your answer to two decimals)
A nuffnuff is shot at an optimum angle, with speed 23 m/s. How far will it travel horizontally before hitting the ground? (use g = 10 m/s2; round your answer to two decimals)
A nuffnuff is shot at an optimum angle, with speed 13 m/s. How long is it airborne before returning to the ground? (use g = 10 m/s2; round your answer to two decimals)
A nuffnuff shot at an optimum angle, strikes the ground after traveling horizontally a distance of 19 meters. With what speed was it thrown? (use g = 10 m/s2; round your answer to two decimals)
A nuffnuff is shot at an angle of 32 degrees to horizontal with speed of 29 m/s. How far will it travel horizontally before hitting the ground? (use g = 10 m/s2; round your answer to two decimals)
Explanation / Answer
(1) Here, height of the ball above the ground, h = 15 m
Find the time when it strikes the ground.
Use the expression -
h = u*t + (1/2)*g*t^2
=> 15 = 0 + 0.5*10*t^2
=> t^2 = 15/5 = 3
=> t = 1.732 s
Therefore, horizontal distance covered by the ball before it strikes the ground -
d = v*t = 29 * 1.732 = 50.23 meter (Answer).
(2) Here, given in the problem h = 39 m
use the same expression as above -
h = u*t + (1/2)*g*t^2
=> 39 = 0 + 0.5*10*t^2
=> t^2 = 39/5
=> t = 2.79 s
Hence, the speed of the ball with which it is thrown -
v = d/t = 12/2.79 = 4.30 m/s (Answer).
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