1. 8 th Science-Force and Newton’s Laws

2. Newton’s First Law Also known as the Law of Inertia States that an object in motion stays in motion and an object at rest remains at rest unless acted on by an unbalanced outside force

3. Newton’s First Law Inertia: a property of matter that describes the tendency of an object to resist changes in its state of motion (The more mass an object has, the greater its inertia) (ex: 18 wheeler vs. compact car), seatbelts,

4. Section 1: Newton’s Second Law For any object, the greater the force that’s applied, the greater its acceleration will be Relates the net force on an object (F) to the object’s mass (m) and acceleration (a) Force, mass and acceleration are connected

5. Friction Objects slow to a stop when moving freely—due to friction The force that opposes motion between two surfaces that are touching ea/other Amt. of friction depends on kinds of surfaces and the force pressing the surfaces together

6. Types of Friction: Static Friction: friction between two surfaces that are not moving past ea/other Sliding friction: force that opposes the motion of two surfaces sliding past ea/other Rolling friction: friction between a rolling object and the surface it rolls on

7. Air Resistance: The force on an object opposite the force of gravity when an object falls toward Earth Effects anything that moves in Earth’s atmosphere The amount of air resistance on an object depends on the speed, size and shape of the object

8. Section 3: Newton’s Third Law Describes action/reaction pairs When one object exerts a force on a second object, the second one exerts a force on the first that is equal in size and opposite in direction OR: “to every action force there is an equal opposite reaction force”

9. Remember: Action/Reaction forces are acting on different objects Even though forces are equal, they are not balanced

10. Rocket Propulsion Rockets use the principle that as the rocket exerts force on gases and causes them to escape out the back of the rocket, the gases exert an opposite but equal force on the rocket propelling it forward Also: stepping out of a canoe example