A cubical block of mass m and edge a slides down a rough inclined plane of inclination theta with a - Physics - System Of Particles And Rotational Motion

Question

A cubical block of mass m and edge a slides down a rough inclined
plane of inclination theta with a uniform speed Find the torque of
normal force acting on the block about its centre

Dinesh Pandey · Accepted Answer

Dear Student,

The block moves down the incline with uniform speed and therefore the net force along the incline is zero
Thus,f-mg sinθ=0f=mg sinθThe gravitational force due to symmetry about the center produces no torque
Since the only force acting on the block are gravitational force mg, normal force N ang frictional force F,the net torque is provided only by the later two forces
Therefore,τnet=τF+τNBut the block does not roll and therefore the net torque is zero
τF+τN=0τN=-τFτN=-Fa2τN=-12mga sinθThus the torque due to normal force is in clockwise direction

A cubical block of mass m and edge a slides down a rough inclined plane of inclination theta with a uniform speed. Find the torque of normal force acting on the block about its centre.