Physics - NLM Question with Solution | TestHub

Equation of motion of $m_1=10\mathrm{kg}$ mass is $F_1=m_1{a}_1=10\times 12=120\mathrm{N}$ Force on 10 kg -mass is 120 N to the right. As action and reaction are equal and opposite, the reactions force $F$-on 20 kg mass $F=120\mathrm{N}$ to the left. $\therefore$ Equation of motion of mass $m_2=20\mathrm{kg}$ is $\begin{array}{rl}200-F& =20a_2\\ 200-120& =20a_2\\ 20a_2& =80\\ a_2=\frac{80}{20}& =4\mathrm{m}/{\mathrm{s}}^2\end{array}$