Question

How fast should a man of mass 60 kg run so that his kinetic energy is 750 J?

Answer 1

Given that:

• Mass of a man = 60 kg
• Kinetic energy = 750 J

Need to find:

• Velocity of a man = ?

Solution:

The formula of velocity of a man —

${\qquad}{ \bigstar{ \boxed{ \sf{k.e. = \frac{1}{2} m{v}^{2}}}}}$

According to the question —

$\sf \implies \: k.e. = \frac{1}{2} \times 60 \times {v}^{2} \\ \\ \sf \implies \: 750 = \frac{1}{2} \times 60 \times {v}^{2} \\ \\ \sf \implies \: {v}^{2} = \frac{2 \times 750}{60} \\ \\ \sf \implies \: {v}^{2} = 25 \\ \\ \sf \implies \: v = \sqrt{25} \\ \\ \sf \implies \: v = 5 \frac{m}{s}$

Hence,the velocity of a man is 5 m/s.