1. Free Body diagrams and problem solving
AP Physics 1

2. 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
FBD

3. TWO types of Friction

4. 3 Common Forms of Friction

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

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

7. Example #1 How much does a 0.25 kg apple weigh?
What is the mass of a 15 N toy car?

8. Example #2
A horizontal net force of 25 N acts on a 12 kg object. What is the acceleration of the object?

9. Example #3
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 Normal Force

10. Example #4
Suppose a 5kg box is being pulled by a 50 N force at an angle of 30o above the horizontal. The box accelerates horizontally at 1 m/s2.
Calculate the Force of Friction
Calculate the Normal Force

11. Example #5
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?

12. Example #6
What is the coefficient of kinetic friction between the crate and the floor?
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.
FBD