Topic 1 Equilibrium

(a)    State the condition for equilibrium

(b)    Give two examples.

Topic 2 Incline Plane

(a)    Show that, for the force parallel to the plane,

(b)    Show that for the force perpendicular to the plane,

Topic 3 Friction

Define the coefficient of friction.

Topic 4 Center of Gravity

(a)    How can you find the center of gravity?

(b)   Why is it useful?

Examples

A tug-of-war is being held between two families on a Memorial Day picnic. Each family pulls on a rope with a force of F while the center of the rope is weighted down by a picnic basket of mass m. The rope on both sides of the basket makes the same angle with the horizontal. What is magnitude and direction of the tension in the rope?

A picture frame of mass m and width W is supported by a wire of L length. What is the magnitude and direction of tension in the wire?

A box of tools of mass m is resting on a wooden plank of length L, one end of which is on the ground and the other end of which is supported by a certain rung of a ladder. If the coefficient of friction between the tool box and the plank is  µ and the tool box does not slide, what is the maximum height of that rung of the ladder?

Textbook Problems