1. Sign in Handouts Phones up

2. Objectives Calculate the effect of forces on objects,
law of inertia,
the relationship between force and acceleration
the nature of force pairs between objects;
Develop and analyze free body diagrams that illustrate these forces;

3. Inertia
Inertia – the tendency of an object to resist changes in velocity
An object that is at rest will remain at rest, and an object that is moving will continue to move in a straight line with constant speed
A more massive object has a greater tendency to resist changes in its state of motion.

4. Force FORCE - A push or pull exerted on an object UNITS = NEWTONS (N)
Has a magnitude and direction (VECTOR!)
Two kinds of forces:
Contact force – a force caused by direct physical contact between two objects
Field force – forces exerted without touching
Gravitational force
Electromagnetic force
Nuclear force
Friction force- forces that resist motion
UNITS = NEWTONS (N)

5. Force
Spring force: The force exerted by a compressed or stretched spring upon any object that is attached to it.
Tension Force: Force that a string or rope exerts 

6. Frictional Forces Frictional Forces – forces that resist motion
Depends on the surface materials of each object and the contact force between the objects.
STATIC FRICTION: the amount of force needed to start an object moving that is currently at rest
KINETIC FRICTION: the amount of force needed to keep something moving at a constant velocity

7. Forces
Give an example of a frictional force you use daily.

8. Free Body Diagram
FREE BODY DIAGRAM - A physical representation that shows the forces acting on a system
Always draw the force vectors pointing away from the object (even when the force is a push)
Make the length of the arrow proportional to the size of the force
Label each force
Example:

9. Unbalanced Force
Unbalanced Force: force that does not become completely balanced (or canceled) by the other individual forces.
Net Force: the vector sum of all the forces that act upon an object.

10. What happens when forces are unbalanced?
A net force (or unbalanced force) causes an acceleration – changing its speed, its direction, or both
Give an example of a balanced force.
Give an example of an unbalanced force.

11. Foldable

12. Foldable
Balanced 0N

13. Foldable
Unbalanced -40N (Left)

14. Foldable
Unbalanced -20N (left)

15. Foldable
Unbalanced UP