A ball is thrown vertically downward with a velocity of 20m/s from the top of a tower. It hits the ground after some time with a velocity of 80m/s. The height of the tower is : (g=10m/s2)
A
320m
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B
300m
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C
360m
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D
340m
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Solution
The correct option is B300m
Let the height of the tower is h.
The motion of the ball is constant accelerating motion with acceleration g=10m/s2.
Initial velocity of ball, u=20m/s
Final velocity of ball, v=80m/s
According to equation of motion for constant accelerating motion,
(Here, downward direction is negative and upward direction is positive)