# Q. 10.     An object of mass $40 \; kg$ is raised to a height of $5\; m$ above the ground. What is its potential energy? If the object is allowed to fall, find its kinetic energy when it is half-way down.

S Sanket Gandhi

The potential energy of an object of mass m and at the height at h is given as    =  mgh

The potential energy of the given object is :

$P.E.\ =\ mgh\ =\ 40\times 10\times 5\ =\ 2000\ J$

The potential energy is being converted into the K.E..

Thus at half-way kinetic energy of the object is :

$K.E.\ =\ \frac{P.E.}{2}\ =\ \frac{2000}{2}\ =\ 1000\ J$

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