Question

a body of mass 500 gram is moving with a speed 20m/sec. A force acts on it which makes it to move with a speed 30m/sec. Find the change in the kinetic energy of the body and the work done by the force on the body?

Answer 1

Mass=0.5 Kg

Intial Speed(u)=20 m/s
Final Speed(v)=30 m/s

Change In Kinetic Energy
$\frac{1}{2} \times mass \times {v}^{2} - \frac{1}{2} \times mass \times {u}^{2} \\ \frac{1}{2} \times 0.5 \times {30}^{2} - \frac{1}{2} \times 0.5 \times {20}^{2} \\ = 0.25 \times {30}^{2} - 0 .25\times {20}^{2} \\ = 225 - 100= 125J$
Change In Kinetic Energy=125J
Work Of Force=125J