1. Chapter 2 Forces

2. 2.1 – Forces change motion A force is a push or a pull
A force can change motion, speed, and direction

3. Types of Forces
Contact Force
Gravity
Friction

4. Contact Force
When one object pushes or pulls another object by touching it, the first object is applying a contact force to the second.

5. Gravity Gravity is the force of attraction between two masses
The strength of the gravitational force between two objects depend on their masses.

6. friction
Friction is a force that resists motion between two surfaces that are pressed together.

7. Size and direction of forces
Force is a vector (like velocity) – it has both size and direction.

8. Balanced and unbalanced forces
Net Force - The overall force acting on an object when all the forces are combined.
If the net force is equal to zero (0), the forces acting on the object are balanced. The object does NOT move.
Only unbalanced forces can change the motion of an object.

9. An example of balanced forces
If both individuals apply the same amount of force, then the box will NOT move.

10. Another example of balanced forces
Even though this guy hits the wall hard, the wall returns the same amount of force, thus the forces are balanced. The wall doesn’t move.

11. Newton’s first law relates force and motion
Objects at rest remain at rest, and objects in motion remain in motion with the same velocity, unless acted upon by an unbalanced force.

12. inertia
The resistance of an object to a change in the speed or the direction of its motion.