-Motion is the state in which one object’s distance from another is changing

-Motion is the state in which one object’s distancefrom another is changing.

-Motion is the state in which one object’s distancefrom another is changing.

How do you know that something is moving?

• A reference point is needed to determine if an object is in motion.

• A reference point is a place or object used to determine if an object is in motion

• An object is in motion if it changes position relative to the reference point.

• Earth rotates on its axis at 1,100 mph

• Earth orbits the Sun at 68,000 mph

• The whole galaxy rotates at 490,000 mph

Speed = distancetime

A snail crawls 10 feet in 5 minutes.What is the speed of the snail?

Constant Speed

• When an object is traveling at the same speed while it is in motion

• Example: using the cruise control on a car

It has bothspeed and direction.

Do all these planes have the same speed?

Istheirvelocitydifferent?

What is acceleration?• Rate at which

velocity changes

• In science, it means speed up, slow down, or change direction

Calculating acceleration

• Acceleration= Final velocity-Initial velocity

time

A = VF-VI

t

• A car starts from rest and accelerates over a time of 5.21 seconds for a distance of 110 m. Determine the acceleration of the car.

Newton’s First Law of Motion-

An object at rest or in motion will remain that way until acted upon by an outside unbalanced force.

Common Example of First Law

• People commonly encounter the 1st law while sitting in a fast moving vehicle that comes to a sudden stop

1st Law

• An outside force (the collision) stop the vehicle, but passengers continue to move long after the vehicle is stopped

1st Law

• Why were the passengers thrown forward?

Newton's Laws of Motion

Newton’s First Law:            

Q: Why do we not observe this usually?

Force = mass X acceleration

Newton’s 2nd Law

F = Ma

Newton's Laws of Motion

Newton’s Second Law:               

F ma

What does F = ma say?F = ma means that the force of an object comes from its mass and its acceleration.

Something very small (low mass) that’s changing speed very

quickly (high acceleration), like a bullet, can still have a

great force. Something very small changing speed very slowly

will have a very weak force.

Something very massive (high mass) that’s changing speed very slowly (low acceleration), like a glacier, can still have great force.

2nd Law

• They both have the same acceleration (gravity)

• That means the one with more mass will have more force when it hits the ground.

• Which will have more force, the elephant or the hockey puck?

Newton’s 3rd Law -For every action,there is an equaland oppositereaction.

3rd Law

• Forces come in pairs – action and reaction• If body A exerts a force on body B, the body

B exerts an equal and opposite force on body A

Newton's Laws of Motion

Newton’s Third Law: To every action, there is an equal and opposite reaction.

Example

• The engine pushesgases down.

• The rocket goes up.