A body of mass $10 k g$ is kept at a height of $5 m$ . It is allowed to fall and reach the ground.
What is the kinetic energy possessed by the body just before hitting the ground? Take $g = 10 m s^{- 2} .$

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Solution

$m = 10 k g$ $g = 10 m / s^{2}$ $h = 5 m$
Initial energy of the system= $P . E = m g h =$ $10 \times 10 \times 5 = 500 J$
Since total mechanical energy (KE+PE) remains conserved.
At ground height is zero so PE become zero ,all PE is lost and converted into KE.
Therefore, initial potential energy = Final kinetic energy
So in this case when body reachs the ground potential energy would be equal to zero.
So, final kinetic energy = initial potential energy = $500 J$

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