Question

Define work energy theorem. [3 MARKS]

Answer 1

Each point: 1 Mark

1. The energy associated with work done by the net force doesn’t disappear. It transform into the kinetic energy of the body. It is called as Work energy theorem. If the speed of the body increases the work done on the body is positive. If the speed of the body reduces, kinetic energy of the body decreases or work done is negative.

2.${KE}_1=\frac{1}{2}m{u}^2,{KE}_2=\frac{1}{2}m{v}^2{W}_{net}=F\times s\times cos\left(0^{\circ }\right)=F\times s;W_{net}=0\text{and change in velocity}=0$

3. ${KE}_1=\frac{1}{2}m{u}^2,{KE}_2=\frac{1}{2}m{v}^2{W}_{net}=F\times s\times cos\left({180}^{\circ }\right)=-F\times s;W_{net}<0and\text{Change in velocity}<0$