Question

How fast should a man of mass 50 kg run so that its kinetic energy is 750 J

Answer 1

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Answer 2

Given: The mass of a man is 50 kg.

He runs with a kinetic energy of 750 J.

To find: The velocity of the man.

Solution:

A body possesses kinetic energy when it is in motion.

We know that the kinetic energy of a body depends on its velocity and mass.

It is known that, kinetic energy can be obtained by the following equation:

Kinetic energy = $\frac{1}{2}$ × mass × $velocity^{2}$

$& \Rightarrow 750=\frac{1}{2}\times 50\times velocit{{y}^{2}} \\ & \Rightarrow velocit{{y}^{2}}=\frac{750\times 2}{50} \\ & \Rightarrow velocit{{y}^{2}}=15\times 2 \\ & \Rightarrow velocit{{y}^{2}}=30 \\ & \Rightarrow velocity=\sqrt{30} m/s \\ & \Rightarrow velocit{{y}}=\text{5}\text{.477} m/s$

Hence, the velocity with which the man runs is 5.477 m/s.