Free Body diagrams and problem solving AP PHYSICS

Free Body Diagrams A pictorial representation of forces acting on an object complete with labels. Consider the box being pulled to the right by a rope across the floor

TWO types of Friction

3 Common Forms of Friction

Sliding Friction Sliding Friction Depends on Two Things: 1. 2.

Rolling Friction Fluid Friction Depends on Three Things: 1. 2. 3.

Example 1 A 10-kg box is being pulled across the table to the right at a constant speed with a force of 50N. Calculate the Force of Friction Calculate the Force Normal

Example 1 Continued A 10-kg box is being pulled across the table to the right at a constant speed with a force of 50N. Calculate the Force of Friction Calculate the Force Normal mg

Example 2 Suppose the same box is now pulled at an angle of 30 degrees above the horizontal. Calculate the Force of Friction Calculate the Force Normal

Example 2 Continued Suppose the same box is now pulled at an angle of 30 degrees above the horizontal. Calculate the Force of Friction Calculate the Force Normal FN Fa Fay Ff 30 Fax mg

Example 3 A 10-kg box is being pulled across the table to the right by a rope with an applied force of 50N. Calculate the acceleration of the box if a 12 N frictional force acts upon it.

Example 4 A crane applies a force of 500N to a 25kg crate as it is raised into the air. What is the acceleration of the crate?

Example 5 A 1500 N crate is being pushed across a level floor at a constant speed by a force F of 600 N at an angle of 20° below the horizontal as shown in the figure. What is the coefficient of kinetic friction between the crate and the floor?