Question

A block of mass $40\, kg$ slides over a surface, when a mass of $4\, kg$ is suspended through an inextensible massless string passing over frictionless pulley as shown below. The coefficient of kinetic friction between the surface and block is $0.02$. The acceleration of block is. (Given $g=10\, ms ^{-2}$.)

• A. $1\, ms ^{-2}$
• B. $1 / 5\, ms ^{-2}$
• C. $4 / 5\, ms ^{-2}$
• D. $8 / 11\, ms ^{-2}$

Answer 1

Answer: (D)

For $4 kg$ block
$4 g - T =4 a$
For $40 kg$ block
$T -40 g \times 0.02=40 a$
Adding both eq.
$40-8=44 a$
$a=\frac{32}{44}=\frac{8}{11} m / s ^{2}$