Question

Two masses of 3 kg and 4 kg are connected at two ends of a light inextensible string that passes over a frictionless pulley. Find the tension in the string when the masses are released (g = 9.8 ${m/s}^2$).

• A. 43.6 N
• B. 53 N
• C. 22 N
• D. 33.6 N

Answer 1

The correct option is D 33.6 N

» smaller mass = $m1=3kg$

» larger mass =$m2=4kg$

» Tension = T

» For mass $m_1$

=> $T-m_{1}g=ma$ ____eq(1)

» For mass $m_2$

=> $m_{2}g-T=m_{2}a$. ____eq(2)

» By eq(1) + eq(2)

=> $(m_2-m_1)g$ = $(m_1+m_2)a$

=> $a=(m_2-m_1)g/(m_1+m_2)$

=> $a=(4-3)\times 10/(4+3)$

=>$a=1\times 10/7=10/7$

=> $a=33.6m{s}^{-}2$