Question

Three blocks are connected to each other with light inextensible strings as shown in the figure given below. Tension $T_1$ and $T_2$ are respectively

• A. 100 N, 20 N
• B. 20 N, 100 N
• C. 60 N, 32 N
• D. 32 N, 60 N

Answer 1

The correct option is D 32 N, 60 N

$F_1=100N,F_2=20N$
Net force $F=F_1–F_2=80N\left(along{F}_1\right)$
F = ma
$m=(m_1+m_2+m_3)=(3+7+10)=20kg$
$a=\frac{80}{20}=4m/s^2$
Each block will move with an acceleration of $4m/s^2$.
Net force acting on block of mass 3 kg is
$T_1–20=3\times 4$
$\Rightarrow T_1=32N$
Net force acting on block of mass 7 kg is
$T_2–T_1=7\times 4⟹T_2–T_1=28$
$⟹T_2=28+32=60N$