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Question
Give the magnitude and direction of the net force acting on a stone of mass 0.1 kg, just after it is dropped from the window of a stationary train. Neglect air resistance.
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Solution
1 N; vertically downward
Mass of the stone, m = 0.1 kg
Acceleration of the stone, a = g = 10 m/s2
According to Newton's second law of motion, the net force acting on the stone is:
F = ma = mg
= 0.1 × 10 = 1 N
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