Q

A child throws a 1/4 kg ball vertically upward. His hand moves upward by 10 cm and the ball leaves it at 2 m/s. Find the constant force exerted to throw the ball.

RRB Group D 24/10/2018 / Shift-III 2018
✓ Answer: D 5 N
The source gives D using a = v²/(2s) = 20 m/s² and ma = 5 N. This is the net force; including gravity, the hand's upward force is m(a + g) ≈ 7.5 N. The printed key is retained.
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