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InterviewSolution
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In which of the following cases the net force acting on the body is not zero?A. A drop of rain falling down with a constant speed.B. A cork of mass 10g floting on the surface of water.C. A car moving with a contant speed of `20kmh^(-1)` on a rough road.D. A pebble of mass `0.05kg` is thrown vertically upwards. |
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Answer» Correct Answer - D As the rain drop is falling down with a constant speed, its acceleration, `a=0` . Hence, net force on the `drop=ma=0` . As the cork is floting on the surface of water, its weight is balanced by the upthurt. Hence, net force on the cork is zero. The force exerted by the engine is balance by the friction due to rough road. as the car is moving with constant velocity, its acceleration `a=0` . Hence, net force on the car, `F=ma=0` . Whenever a body is thrown vertically upward gravitational pull of earth gives it a unform acceleration, `a=g` in downward directiion. Hence, net force on the `pebble=mg:0.05xx10=0.5N` vertically downwards. |
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