1. My Jedi Science Students…
USE THE FORCE! I CAN describe the types of forces and their effects on the motion of objects.

2. What is a force?

3. What is a force? A FORCE is a push or a pull
Forces are vectors (include size and direction)
Unit = NEWTON (N)
All forces are exerted from one object to another

4. 6 Types of Forces ELECTRICAL – positive and negative charges
GRAVITY – all objects with mass pull on other objects
NUCLEAR – holds atoms together
MAGNETIC – north and south
MECHANICAL – physical push or pull
FRICTION – resistance to motion when sliding

5. Net Forces
The force that an object feels when multiple forces are acting on it.

6. Net Forces
When two forces act in the same direction you ADD them to find the net force.
When two forces act in the opposite directions you SUBTRACT them to find the net force.

7. Balanced vs Unbalanced Forces
Net force on an object is EQUAL TO ZERO
Does not produce a change in motion
Net force on an object is GREATER THAN ZERO
Produces a change in motion

8. Balanced vs Unbalanced Forces

9. Balanced vs Unbalanced Forces

10. What is friction?
Friction = force that opposes the motion of two surfaces that are touching
Always happens in the direction opposite of the direction of motion

11. Friction - SLIDING Explanation – opposes the motion of sliding objects
Labeled Picture
Explanation – opposes the motion of sliding objects
Additional Example – sledding, brakes on a car, writing with pencil, moving heavy furniture

12. Friction - STATIC Labeled Picture
Explanation – frictional force on a non-moving object
Additional Example – pushing a heavy box, skis sticking to snow when not moving

13. Friction - ROLLING
Labeled Picture
Explanation – friction between wheels and a flat surface
Additional Example – bikes, cars, trains, skateboard, furniture dolly, rolling suitcase

14. Friction - FLUID Labeled Picture
Explanation – force that opposes the motion of objects traveling in liquids or gases
Additional Example – walking on a wet floor, swimming, hand out a moving car’s window

15. GRAVITY – What is it?
Force of attraction between two objects due to their masses.

16. The Law of Universal Gravitation
All objects in the universe ATTRACT each other through gravitational force.
Gravitational force INCREASES as mass INCREASES. (more mass = more gravity)
Gravitational force DECREASES as distance INCREASES. (more distance = less gravity)

17. Weight vs Mass WEIGHT = measure of the gravitational pull on an object
Unit = Newtons
Can change depending on location
MASS = amount of matter in an object
Unit = kilogram
Stays the same everywhere