Question

Three blocks of masses $3kg,0.6kg$ and $1kg$ are connected by a string passing over two smooth pulleys attached at the two ends of a frictionless horizontal surface. The acceleration of $3kg$ mass is :

• A. $1{ms}^{-2}$
• B. $4.35{ms}^{-2}$
• C. $8.43{ms}^{-2}$
• D. $12.98{ms}^{-2}$

Answer 1

Answer: (B)

$4.35{ms}^{-2}$

Here,
for $0.6kg$ block: $T_1-T_2=0.6a....\left(1\right)$
for $1kg$ block: $1a=T_2-1g...\left(2\right)$
for $3kg$ block: $3a=3g-T_1...\left(3\right)$
$\left(2\right)+\left(3\right),4a=(T_2-T_1)+2g=-0.6a+2g$
$4.6a=2g\Rightarrow a=\frac{2\left(10\right)}{4.6}=4.35m/s^2$
Acceleration of $3kg$ mass is $a=4.35m/s^2$