Question

What is the wore done to change the velocity from 5m/s to 2m/s for a mass of 20kg?

Answer 1

Concept :

Work done = change in kinetic energy .

Calculate the work done

Work = $\frac{1}{2}mv^2-\frac{1}{2}mu^2$

         = $\frac{1}{2}m(v^2-u^2)$

         = $\frac{1}{2}\times 20\times(5^2-2^2)$

         = $10\times(25-4)$

         = $10\times21$

         = $210$

ANSWER :

The work done is 210 J