# Newton three laws

## Newtons first law:

an object at rest will remain at rest until a net force is acted on;or an object at rest will stay in constant motion unless a net force acts on it.

• law of inertia
Newton's 1st Law of Motion for children

## Newtons second law:

acceleration of an object is the same direction that the net force is applied on an object.

• f=ma force= mass x acceleration a=f/m
• greater the force; the greater the acceleration
Newton's 2nd Law of Motion

## Newtons third law:

for every action there is an equal and opposite reaction

• greater the mass, greater the momentum
• ex. ball bounces back up off the floor
Newtons 3rd law of Motion

## Friction:

force that opposes motion between 2 surface that are touching each other

• ex. rubbing your hands together and they get hot
• microseconds: area where surface stick together and friction is caused

## Types of friction:

1.static friction: friction between 2 surface that are not moving past each other
a. it takes more energy to break static friction than any other friction

b. the initial friction that must be overcome in order to start rolling or sliding friction

c. ex. desk sitting still on the floor, ball sitting still

2. sliding friction: 2 surface sliding past each other

a. ex bowling ball sliding down the lane but nit spinning

3. rolling friction: friction between a rolling object and the surface it is rolling on

a. ex. skateboard rolling on cement; car driving down the road

## Air resistance:

opposes the motion of objects that move through air
• the amount of air resistance depends on objects size, shape and speed
• thermal velocity: highest speed an object can fall at a constant speed

## Law of gravity:

2 masses exert an attractive force on each other; 2 masses pull towards each other

• Due to inertia ALL objects will fall with the same acceleration {gravity 9.8m/s/s

## Weight:

gravitational force exerts on an object

• w=mg weight = mass x gravity {gravity =9.9/s/s}

## Projectile Motion:

horizontal and vertical velocities due to gravity, follow a curved path

• ex. throwing a baseball: ball flies horizontal and drops vertical