Aim What are Newtons laws of Motion Do

Aim: What are Newton's laws of Motion? Do Now: What would life be without friction?

FORCE: • The cause of motion (what causes objects to move) • Two types of forces – Pushes – Pulls

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

Balanced force- no motion Unbalanced force- motion in the direction of stronger force

FRICTION – Friction- is the force that opposes motion • Smooth surfaces decrease friction, while rough surface increase friction

Friction

NEWTON’S FIRST LAW An object at rest will remain at rest unless acted on by an unbalanced force. An object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force. called "the law of inertia".

First Law • Inertia – An object at rest 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]

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 http: //toons. artie. com

Examples of Newton’s 1 st Law

NEWTON’S SECOND LAW Newton's second law of motion states that an object accelerates because a force acts on it. The stronger the force, the greater the acceleration. Second Law gives us an exact relationship between force, mass, and acceleration. FORCE = MASS times ACCELERATION OR

Mike's car, which weighs 1, 000 kg, is out of gas. Mike is trying to push the car to a gas station, and he makes the car go 0. 05 m/s/s. Using Newton's Second Law, you can compute how much force Mike is applying to the car.

Example-2 nd law How much force must the football player exert to accelerate a 180 -kg player with the tackling dummy at a rate of 2 m/s^2? Answer is 360 newtons.

Examples of Newton’s 2 nd Law

The truck is in motion, the car is at rest. How do each of these vehicles accelerate? The truck stops moving. The car starts moving. Which one will be the hardest to accelerate? The truck because it has the most mass. file: ///C: /TEMP/Content. IE 5/3 GSE 3 P 1 C/269, 13, Slide 13

Why does the car move [accelerate] when it is hit by the truck? The heavy and moving truck has more force than the small, at rest car. Why does the truck stop moving when it hits the car? The force of the car pushing back on the truck, plus the force of friction between the massive truck and the road slow down, the stop the truck. file: ///C: /TEMP/Content. IE 5/3 GSE 3 P 1 C/272, 14, Slide 14

NEWTON’S THIRD LAW For every action there is an equal and opposite reaction. UP, and AWAY!

3 rd Law examples

The truck hits the car. An action force stops the truck. What is the equal and opposite reaction force? The force that pushes the car forward. file: ///C: /TEMP/Content. IE 5/3 GSE 3 P 1 C/271, 15, Slide 15