1. Forces

2. First we need to define the word FORCE:
The cause of motion (what causes objects to move)
Two types of forces
- Pushes
- Pulls

3. Forces are measured in Newtons
SI unit of force
Symbol: N
Measured by using a spring scale

4. Forces may be balanced or unbalanced
Balanced forces – all forces acting on an object are equal
-There is NO MOTION
Unbalanced forces – one or more forces acting on an object are stronger than others
-There is MOTION
A NET FORCE

5. Friction Force that slows down motion.
There are three different types of friction:
1. Rolling Friction
2. Sliding Friction
3. Fluid Friction

6. Rolling Friction
The friction that exists when a wheel turns on a surface.

7. Sliding Friction
When two objects are rubbing against each other.

8. Fluid Friction
The friction on a solid object as it moves through water.

9. Gravity Force that attracts all objects toward each other
More mass = more gravity
Acceleration because of gravity is 9.8 m/s/s
All objects accelerate at the same rate

10. Newton’s Laws First Law – Inertia
Second Law – Acceleration, Force & Mass
Third Law – Action-Reaction

11. First Law
Inertia
An object at rest [not moving] remains at rest unless acted on by a force [push or pull]
An object in motion remains in motion unless acted on by a force [push or pull]

12. First Law Inertia & Mass Mass is the amount of matter in an object
The more MASS an object has, the more INERTIA the object has.
Bigger objects are harder to start & stop

13. Second Law Acceleration & Force Acceleration & Mass
The more force placed on an object, the more it will accelerate [change its motion]
Acceleration & Mass
The more mass [or inertia] an object has, the more force it takes to accelerate the object

14. Third Law Action – Reaction
Forces are always produced in pairs with opposite directions & equal strengths
For every force there is an equal and opposite force