If \(100 \mathrm{~N}\) force is applied to \(10 \mathrm{~kg}\) block as shown in the diagram, the…

If \(100 \mathrm{~N}\) force is applied to \(10 \mathrm{~kg}\) block as shown in the diagram, the acceleration of \(40 \mathrm{~kg}\) slab is
  1. \(1.65 \mathrm{~ms}^{-2}\)
  2. \(0.98 \mathrm{~ms}^{-2}\)
  3. \(0.5 \mathrm{~ms}^{-2}\)
  4. \(0.25 \mathrm{~ms}^{-2}\)

Solution

Static friction force between \(10 \mathrm{~kg}\) and \(40 \mathrm{~kg}\) block,
\(\begin{aligned} F_s & =\mu_s R=0.6 \times m g \\ & =0.6 \times 10 \times 9.8=58.8 \mathrm{~N} \end{aligned}\) Here, we see that the applied force \((F=100 \mathrm{~N})\) is greater than friction force, hence \(10 \mathrm{~kg}\) block will start motion due to application of \(100 \mathrm{~N}\) force. Due to motion, kinetic friction force \(\begin{aligned} f_k & =\mu_k R=0.4 \mathrm{mg} \\ & =0.4 \times 10 \times 9.8=39.2 \mathrm{~N} \end{aligned}\) \(40 \mathrm{~kg}\) body experiences a force of \(f_k=39.2 \mathrm{~N}\) \(\therefore\) Acceleration of \(40 \mathrm{~kg}\) slab \(a=\frac{f_k}{40}=\frac{39.2}{40}=0.98 \mathrm{~ms}^{-2}\)

Asked in: AP EAMCET 2020 (21 Sep Shift 1)

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