Physics - W.E.P. Question with Solution | TestHub

Given $m=0.36\mathrm{kg},M=0.72\mathrm{kg}$. The figure shows the forces on $m$ and $M$. When the system is released, let the acceleration be $a$. Then $T-mg=ma$ $Mg-T=Ma$ $$a=\frac{(M-m)g}{M+m}=g/3$$ and $T=4\mathrm{mg}/3$ For block m: $$u=0,a=g/3,t=1,s=?$$
$$s=ut+\frac{1}{2}a{t}^2=0+\frac{1}{2}\times \frac{g}{3}\times 1^2=g/6$$ Work done by the string on $m$ is $$\bar{T}\bar{s}=Ts=4\frac{mg}{3}\times \frac{g}{6}=\frac{4\times 0.36\times 10\times 10}{3\times 6}=8\mathrm{J}$$