1. 5.3 Net Force and Equilibrium

2. Net Force
Net Force:
The sum of all forces acting on an object - remember direction!!!

3. Net Force
If the net force is NOT ZERO, there will be a change in an object’s motion.

4. Equilibrium
When the forces are balanced, the net force is zero and the object is in equilibrium. 4

5. Solving Equilibrium Problems
Is this object in equilibrium?

6. Normal Force - occurs when an object is in contact with a surface
- equal to the force pressing the object into the surface

7. The Free Body Diagram
How do you keep track of many forces with different directions?
Draw a free-body diagram that contains the objects, like a book on a table. 7

8. The Free Body Diagram
Draw free body diagrams that illustrate the following forces:
You sit in your desk. Your desk weighs 50 N and you weigh 80 N. Don’t forget to draw the normal force!
A 150 N child rides a 25 N skateboard and moves to the right with a force of 10 N. Rolling friction between the wheels and ground is 5 N. Don’t forget to draw the normal force! 8