Question

Figure shows a uniform block of length $30cm$ having a mass of $3kg$. The strings shows in figure are pulled by constant force $20N$ and $32N$. All the surface are smooth and the strings and the pulley are light. Which of the following is correct:

• A. the acceleration is $8m/s^2$
• B. the force exerted by the $20cm$ part of the rod on the $10cm$ part is $32N$A
• C. the force exerted by the $20cm$ part of the rod on the $10cm$ part is $20N$A
• D. the force exerted by the $20cm$ part of the rod on the $10cm$ part is $24N$A

Answer 1

The correct option is D the force exerted by the $20cm$ part of the rod on the $10cm$ part is $24N$A

$\begin{array}{cc}\text{Correct option is}\left(D\right)& \\ \text{As we know:}& \\ \begin{array}{cc}F& =Ma\\ (32-20)& =3a\\ 4m/s^2& =a\end{array}& \\ \text{on}10cm\text{part}\Rightarrow T-20=M_{0}a& \\ M_0=\frac{3}{30}\times 10& \\ =& 1kg\\ \text{So,}T-20=4& \\ T=24N& \end{array}$