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When an object is falling freely from the height h from the earth's surface its gravitational potential energy decreases gradually but its mechanical energy does not change. |
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Answer» Solution :Because, the gravitational potential ENERGY of the OBJECT at HEIGHT from the earth.s surface is mgh. Now, when the object starts falling freely its height h from the earth.s surface decreases gradually. Hence, its gravitational potential energy goes on decreasing. But, as the freely falling object performs constant accelerated MOTION `(a=g)` in downward direction its velocity goes on increasing uniformly. Hence as per the formula `E_(k)=(1)/(2)mv^(2)` its KINETIC energy goes on increasing. Now, as per the law of conservation of mechanical enregy `deltaE_(k)=-DeltaE_(p)`, the kinetic energy goes on increasing in proportion to the decrease in potential energy. Hence as per the formula `E=E_(p)+E_(k)`, the mechanical energy of the object does not change. |
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