1. Balanced vs Unbalanced Forces

2. Balanced Forces Example #1: Books sitting on a table: GRAVITATIONAL Force pulls down The table pushes up on the books with an equal amount of NORMAL force

3. The books do not move up or down because the downward GRAVITY and upwards NORMAL FORCE are equal in size. THESE FORCES ARE BALANCED . Likewise, the books do not move from side to side because there are also equal forces acting on the sides of the book.

4. The end result is no book movement occurs, because all forces acting on the books are equal in size, and opposite in direction.

5. What would happen to the forces affecting the books if the table were tilted?

6. Forces would become unbalanced, resulting in a change in velocity/acceleration. Draw arrows on your diagram to indicate the forces acting on the books.

7. GRAVITY pulls down Table Pushes up with NORMAL FORCE FRICTION opposes movement Books slide down the table….forces become unbalanced

8. Balanced vs Unbalanced Forces: Define Balanced Forces: Define Unbalanced Forces: Effects of two or more forces cancel each other and they do not change the object’s velocity. Net force = 0 Effect’s of two or more forces DO NOT cancel each other and the object’s velocity changes. Net force > 0

9. Inertia Definition of Inertia: A RESISTANCE to ANY CHANGE in motion. An object at rest will remain at rest, or an object in motion will remain in motion, until a net force acts on the object. Examples: 1. tape ball vs marble rolling towards you at the same speed: the tape ball has a greater resistance to any change in its motion then the marble, because the tape ball has more mass.

11. Car and person are traveling at 100 mi/hr straight Car turns sharply Person keeps moving straight

12. What does Inertia depend on? Mass

14. How does Mass affect Inertia? More mass = more Inertia. There is a greater resistance to any change in motion. It seems more difficult to start moving or to try and stop moving. Less mass = less Inertia. There is a lower resistance to any change in motion. It is easier to change velocity of the object that is already moving, or currently at rest.