1. Forces and Motion

2. Balanced and Unbalanced Forces Net Force= the overall force acting on an object when all of the individual forces are added together.

3. Balanced Force= When all forces acting on an object added up equals zero. An object that is being acted upon by a balanced force is undergoing no change in motion. Examples: 1) A ball sitting still on the floor. 2) A ball rolling in a straight line at a constant speed.

4. Unbalanced force= when all the forces acting on an object are added up and the sum is something other than zero. An object experiencing an unbalanced force will be changing motion, so it would either be changing speed, direction or both. Example 1: An orange is sitting on a table. Balanced or Unbalanced?

5. Example 2: A car has a net force that equals 0. Balanced or Unbalanced? Example 3: A box has the following forces acting on it: 5 N to the right, 5 N to the left, 8 N straight down, and 8 N straight up. Balanced or Unbalanced? A car is going around a curve at a constant 55 Km/h. Balanced or Unbalanced?

6. Normal force= the force exerted by an object to balance an outside force acting on it. Example: When you sit on a chair, the chair exerts a normal force on your body that is equal to the force of gravity pulling your mass toward the Earth.

7. Contact and Noncontact Forces Contact force= must touch an object to change its speed or direction. Friction is an example of a contact force. Noncontact forces= can act on objects from a distance. Gravity and Magnetism are the two most common noncontact forces.

8. Gravity= a force that pulls two objects with mass toward each other. The size of the gravitational force depends on two factors: 1) the masses of the objects and 2) the distance between the objects. Weight is the force that is applied to an object due to gravity.