Ablock having mass m slides down an inclined plane. the force of friction between the block and the inclined plane is f, the block's weight is m g, and the normal force is n. (a) draw a free – body force diagram showing the forces acting on the block. (b) write down all relevant newton’s equations for a given situation.
the left arrow
Friction is a force that opposes the motion of an object. Friction is due to the contact between the surface of the object in motion and the surface on which the object is moving, and its direction is always opposite to the direction of motion of the object.
In this problem, we see that the object is moving towards the left: therefore, the friction must act towards the right, as shown by the left arrow.