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 a frictionless pulley as shown below. The coefficient of kinetic friction between the surface and block is 0.02. The acceleration of the block is ______.

(Given g = 10 ms^-2.)

 

Options

• 1 ms^-2

• 1/5 ms^-2

• 4/5 ms^-2

• 8/11 ms^-2

Answer 1

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 a frictionless pulley as shown below. The coefficient of kinetic friction between the surface and block is 0.02. The acceleration of the block is 8/11 ms^-2.

Explanation:

The given figure's FBD (free body diagram) is as follows:

  

Hence, f_r = μN

= 0.02 × 400

= 8 N

Then, 40 – T = 4a

`a = 32/44 = 8/11` m/s²