Question

A block of wood of mass 4 kg placed on an inclined plane, moves down the plane with
constant speed when the angle of inclination is 20°. Calculate the force of sliding friction
between the block and surface of the plane. Given g=9.8ms​

Answer 1

Answer:

Mass of the block  m=8 kg

Acceleration of the block  a=0.4m/s2

Since the block is sliding down the plane, so friction force acts backwards as shown.

Equation of motion along the inclined plane :  

ma=mgsin30o−f

We get  f=mgsin30o−ma

∴  f=(8)(10)(0.5)−(8)(0.4)

⟹f=36.8 N