essential questions who discovered the three laws of motion? what is newton’s second law & how...

Essential Questions• Who discovered the Three

Laws of Motion?• What is Newton’s Second

Law & how does it apply to motion?

Newton’s First Law

“An object at rest tends to stay at rest and an object in motion tends to stay

in motion unless acted upon by an unbalanced force.”

More Laws of Motion

• Newton’s First Law of Motion states that if you kick a ball, the ball will move.

• Newton’s Second Law of Motion says that when a force acts on an object, the object accelerates. – If you kick the ball harder, it will move faster.– It also tells you that a heavy ball is harder to

move than a lighter ball.

Newton’s Second Law

Force equals mass times acceleration.

F = maAcceleration: a measurement of how quickly an object is changing speed. (Acceleration occurs when an object speeds up,

slows down, or changes its direction of motion... ANY CHANGE IN MOTION IS ACCELERATION)

Mass: the amount of matter in an object

NEWTON’S SECOND LAW

The more force that is applied, the more the object

will accelerate.

NEWTON’S SECOND LAW

The object will accelerate in the direction of the force.

Newton’s Second Law of Motion

• A long row of shopping carts takes more force to move than one empty cart requires.

Takes more force to move

NEWTON’S SECOND LAWThe more mass an object has,

the harder it is to accelerate.The less mass an object has, the easier it is to accelerate.

This truck takes more to accelerate because it hasa lot of mass.

Let’s Look at it This Way..• A car will stop suddenly if the driver slams

on the brakes.• However, if the driver applies the brakes

gently, the car gradually slows down.

What does F =MA mean?Force is directly proportional to mass and acceleration.

Imagine a ball of a certain mass moving at a certain acceleration. This ball has a certain force.

Now imagine we make the ball twice as big (double the mass) but keep the acceleration constant. F = ma says that this new ball has twice the force of the old ball.Now imagine the original ball moving at twice the original acceleration. F = ma says that the ball will again have twice the force of the ball at the original acceleration.

What does F = ma say?F = ma basically 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 baseball,

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.

Let’s Review• What is the effect of a car’s

acceleration if six people ride in the car instead of

one?

Let’s Review• Acceleration is produced by _________.

– A.) masses

– B.) forces

– C.) velocity

– D.) pressure

Let’s Review• True or False

If… Force = mass x acceleration

Then… Acceleration = force / mass (net force)

Acceleration…

• Remember our question from the beginning of class?

If someone told you that a car was accelerating, what would that mean to

you?

• What would you say now?

How is slowing down acceleration?• Acceleration in the same direction as

velocity speeds up an object. • Acceleration directed opposite of velocity

slows down an object. • Acceleration on an object with zero

velocity makes the object START to move in the direction of the acceleration.

Newton’s 2nd Law CentersStation 1:

Eraser RacersStation 2:

Speed RacersStation 3:

Weighty SituationStation 4:

Speeding TrainStation 5:

Explaining Newton’s LawsStation 6:

Taking notes