Question

Calculate the velocity of a moving train with a mass 10,000kg and 150,000J of energy.

Answer 1

Kinetic energy possessed by moving train is $E_k = 150000J$.

And mass $m = 10000kg$.

The formula for kinetic energy is $E_k = \frac{m\times v^2}{2}$.

Solve for velocity:

$E_k = \frac{m\times v^2}{2}\implies 2E_k = m\times v^2$

$v^2=\frac{2E_k}{m}\implies \underline{v = \sqrt{\frac{2E_k}{m}}}$

Now put in the data:

$v = \sqrt{\frac{2\times150000J}{10000kg}}\approx5.48\frac{m}{s}$