Laws of Motion

Question
CBSEENPH11016721

A body is placed on rough inclined plane having inclination greater than angle of repose. With what acceleration body will slide down the inclined plane?

Solution

Given that angle of inclination is greater than angle of repose. 
So, 
Acceleration of the body is, 
                      space straight a equals straight g left parenthesis sinθ minus μcosθ right parenthesis.

Question
CBSEENPH11016724

A body is projected up on a rough inclined plane. What is the retardation of the body?

Solution

When a body is moving down the inclined plane, coefficient of friction = straight mu
When the block is at rest on the plane, frictional force is mg sin straight theta
When the block is moving down the plane, f = u mg cos straight theta
Retardation of the body is given by, 
space space space straight a equals straight g left parenthesis sinθ plus μcosθ right parenthesis

Question
CBSEENPH11016726

A body is placed on rough inclined plane having inclination θ less than angle of repose ϕ. What is the force of friction between the body and the inclined plane?

Solution

The force of friction between the body and the inclined plane is , 
                       f =space space space space mg space sinθ.

Question
CBSEENPH11016727

A body is placed on the rough inclined plane having inclination θ greater than angle of repose ϕ. What is the force of friction between the body and inclined plane?

Solution

A body placed on the rough inclined plane has angle of inclination greater than angle of repose. 
So, 
Force of friction between the body and the inclined plane is given by, 
f = space space mg space cosθ space tanϕ.