1. Forces and Motion

2. What is a force? A push or a pull
Force is something that causes a body to move, change its speed or direction, or distort (change) its shape
Forces can be balanced causing no change in motion (meaning to continue at the same speed or to stay motionless)
Unbalanced forces cause a change in motion due to one force being greater than the other

3. What is motion?
Motion is a change in position of an object compared to a reference point
Reference points are usually stationary objects on Earth like a tree or building
Forces cause motion

4. More on Motion
Speed is the rate an object moves and is calculated as S = D/T where d=distance and t=time
Velocity is an object’s speed with direction
ex: The car was traveling 85km/h to the south
Acceleration is the change in velocity of an object, it can be positive (increasing acceleration) or negative when slowing down (deceleration)
Momentum is an object’s mass x it’s velocity (M=mv)

5. Gravity (non-contact) Friction (contact) Magnetism (non-contact)
Some Types of Forces
Gravity (non-contact)
Friction (contact)
Magnetism (non-contact)
Elastic (contact)
Static Electricity (non-contact)

6. Gravity
Gravity – A non-contact force of attraction between two objects.
Objects have an attraction to each other. The more mass an object has, the more gravity. That’s why everything falls back to our massive planet!
Newton’s Law of Gravitation
The gravitational attraction between two objects is dependent on the mass of the two objects and the distance between them.

7. More Gravity How do the gravitational forces affect objects?
Acceleration – all objects accelerate at a constant speed of 9.81 M/S2
When all other forces are equal, different objects dropped from the same height will accelerate at the same rate
The more mass, the greater the force an object has
Weight, it is the gravitational pull on the object’s mass
Mass is the amount of matter in an object regardless of the gravitational pull
Projectiles fall in a curved path known as a trajectory

8. Friction A contact force that opposes motion
Results when two objects rub against each other
Friction can be useful as in a car race
Friction can be harmful if you are trying to skate or ski
Rough surfaces increase friction
Smooth surfaces decrease friction

9. Magnetism Magnetism is a non-contact force.
A magnetic field is shown left; notice the bands of force as they move around a magnet. Also, notice the bands of force between two magnets.

10. What Is Energy?
Kinetic Energy – The energy of motion. The more energy an object has, the more force it has.
Potential Energy – The kinetic energy an object potentially has. It is also known as stored energy.

11. Newton’s Three Laws of Motion
Written in 1687
Describe the motion we observe
Explain the forces behind the motion
1st Law = Inertia
2nd Law = F=MA
3rd Law = Action/Reaction

12. Inertia – The First Law Newton’s First Law of Motion
It states that objects at rest stay at rest, and objects in motion stay in motion until a force acts upon them.
Inertia is why seat belts are so important to wear!
It is also why you can pull the rug out from under something.

13. Force = Mass x Acceleration - The Second Law
Newton’s Second Law of Motion
It states that if you increase the force, then the acceleration increases, or if you increase the acceleration, then the force increases.
A little bit of algebra!
You can also change the mass to affect the force.

14. Action/Reaction – The Third Law
This is Newton’s Third Law of Motion
It states that for every action, there is an equal and opposite reaction
This is why a rocket pushes up as the engines push down