Question

In the arrangement shown, the pulleys, strings and the spring balance, all are ideal. If $m_{1}>m_{2}$ , then the reading of the spring balance is

• A. $m_{1}-m_{2}$
• B. $\frac{1}{2}\left(m_{1} + m_{2}\right)$
• C. $\frac{4 m_{1} m_{2}}{m_{1} + m_{2}}$
• D. $\frac{2 m_{1} m_{2}}{m_{1} + m_{2}}$

Answer 1

Answer: (D)

The acceleration of the system $\left(\frac{m_1-m_2}{m_1+m_2}\right) g$ and hence the tension T in the string is $\left(\frac{2 m_1 m_2}{m_1+m_2}\right) g$
The reading of the spring balance is T (in units of force) and T/g(in units of mass).