1. Forces

2. What is a force? Force a push or pull on an object
Forces are described by how strong they are and the direction in which they act.

3. Unbalanced Forces
Unbalanced forces acting on an object will cause an object to start moving, stop or change directions.

7. Inertia
Inertia is the tendency of an object to resist change in its motion.

8. Newton's First Law
An object at rest tends to stay at rest and an object in motion tends to stay in motion unless acted upon by an unbalanced force.

9. Mass Mass is the amount of matter in an object. Not it's weight.
Mass is measured in Kilograms
The greater an objects mass the greater it’s inertia.

10. Newton’s Second Law
The net force on an object is equal to the product of it’s acceleration and it’s mass.
force = mass x acceleration

11. Newton’s Third Law
For every action there is an equal and opposite re-action

12. Friction
The force that one surface exerts on another when the two surfaces rub against each other.
The strength of friction depends on-
The types of surfaces involved
How hard the surfaces push together.

13. Three Kinds Of Friction
Sliding friction-solid surfaces sliding over each other.

14. Three Kinds Of Friction Cont.
Rolling friction-a round solid object rolling over a surface.

15. Three Kinds Of Friction Cont.
Fluid friction- a solid object moving through a liquid or a gas

16. Gravity The force that pulls objects toward each other.
Free fall- when the only force acting on an object is gravity.

17. Gravity Continued Acceleration of objects in free fall is 9.8 m/s².
Objects falling through air experience a fluid friction called air resistance.

18. Weight What is the difference between mass and weight?
Mass is the amount of matter in an object.
Weight is a measure of the force of gravity on an object.
Weight =mass X acceleration due to gravity.
In science weight is measured in Newtons.