3Sample Problem 1A tetherball leans against a smooth, frictionless post. The string is 1.4 m long and the ball has a radius of m with a mass of kg. What is the tension in the rope? What force does the pole exert on the ball?
4Sample Problem 2Two blocks are held in place on a frictionless incline. The mB = 10 kg and mA = 12 kg. The incline is tilted at an angle of 37o to the horizontal. Determine the tension in each rope.
5FrictionFriction is a resistive force. Kinetic friction is resistive to motion and static friction resists motion in the first place.In general, static friction is greater than kinetic friction
6Kinetic FrictionWill always point in a direction opposite to the direction of motionFf = µkFn
7Sample Problem 3A box of mass 25 kg is pushed across a floor at a constant speed of 2 m/sec. What force is needed to push the box if there is a coefficient of friction of 0.2 between the box and the floor?
8Sample Problem 4The weight of the crate is 500 N and there is a coefficient of friction between the crate and the floor of If the worker pulls with a 400 N force, what is the acceleration of the crate?
9Sample Problem 5A pig slides down a chute inclined at 30o. If there is a coefficient of friction between pig and slide of 0.6, what is the acceleration of the pig down the slide?
10Static Friction Resists the desire of an object to move. Range of possibilities though we will typically look at the maximum case.