How is friction used when a body is in equilibrium?

• When a body is in static equilibrium under the action of a number of forces, including friction, the value of friction will be less than or equal to the value of?μR
• When the value of friction is equal to?μR,?the body is in?limiting equilibrium?and is on the point of moving
• When a body is stationary on an inclined plane then it is either in equilibrium or in limiting equilibrium, we cannot assume that?F?=?μR

How is friction used when a body is moving?

• When a body is moving under the action of a number of forces, including friction, the value of friction will be equal to the value of?μR

A wooden block of mass?m?is stationary on a plane inclined at 25° above the horizontal. The coefficient of friction between the block and the plane is μ.? Find the least possible value of μ .

How is friction used for connected particles?

• When two particles are connected by means of a light, inextensible string, friction will act only on any particle that is resting on a rough surface
• On an inclined slope, friction will act in the direction opposite to the direction the particle is moving in or on the point of moving in
• The direction they will move in depends on both the weight of the particles and the angles of the slopes they are resting on
  • Compare the components of the weight in the direction of the motion the particles will move in
  • The particle with the heavier component will move down the slope