Newton’s 1st Law

Law of Inertia

Question?

• What is Newton’s first law of motion?

The Law of Inertia

• The LAW OF INERTIA is Newton’s FIRST law of motion.

Newton’s Law of Inertia

• What does the Law of Inertia say?

• An object in M______ will remain in M______; An object at R______ will remain at R_____, until acted upon by a N___ F_____.

otionotion est

est

et orce

What is inertia?

• Inertia- the tendency of an object to resist any change in its M______. otion

Inertia

• The inertia of an object is related to its MASS. The GREATER the MASS the GREATER the I_____.

• Mass is the amount of MATTER an object has.

nertia

Question?

• Does a bowling ball have the same inertia as a tennis ball? Why?

The Law of Inertia at Work!

The penny is at rest and wants to remain at rest. When the string on the card is pulled with enough force, the penny will REMAIN AT REST.

The dishes are at rest and want to remain at rest. When the table cloth is pulled with enough force, the dishes will REMAIN AT REST.

PULL

The Law of Inertia at Work!An object in motion wants to stay in motion. The person in the car is traveling at the same velocity as the car. When the car stops, the person wants to STAY IN MOTION. That is why you must wear your seatbelts!

The Law of Inertia at Work!An object in motion wants to stay in motion. The test tube and the skateboard it is on is traveling at the same velocity. When the skateboard is stopped, the test tube wants to STAY IN MOTION.

Newton’s Second Law

Force = Mass X Acceleration

F = m X a

Observe what is going on in the picture?

Identify at least 5 forces taking place in the picture below.

Table pushing up on rock

Rock pushing down on table

Boy pulling on rope and rock

Downward force of gravity

Friction between rock and table and rope and hands

What do you believe the relationship is between mass and force?

The more M______ an object has the more F______ required.

The relationship between mass and force….

ass

orce

The relationship between mass and force….

Question….If Marge applied the same amount of force

to the grocery carts below, which will accelerate the slowest? Why?

The more M________ an object has the less it will A ___________.

The relationship between mass and acceleration….

ass

ccelerate

The relationship between mass and force….

Newton’s Second Law says…….

If you apply a F_____________ to a M________ it will A___________.

FORCE

MASSACCELERATE

orce

ass ccelerate

Newton’s 2nd Law says…

FORMULA: Force = Mass X Acceleration

F = m X a

m a

F

X

CAN YOU DERIVE THE UNIT FOR FORCE ?

Force = Mass X Acceleration

= kg X m/s2

m a

F

X

kg X m/s2

kg*m/s2 = NEWTON

FORCE is measured in NEWTONS !

Calculate the force needed to push a truck that has a mass of 2,000 kg with an

acceleration of 0.05 m/s2.

m a

F

X

2,000 kg 0.05 m/s2

100 N

100 N

Calculate the force needed to push a car that has a mass of 1,000 kg with an

acceleration of 0.05 m/s2.

m a

F

X

1,000 kg 0.05 m/s2

50 N

50 N

Calculate the acceleration of a 1,000 kg elephant if a force of 100 N is applied.

m a

F

X

1,000 kg 0.1 m/s2

100 N

100 N

1,000 kg

__?__ m/s20.1 m/s2

Newton’s Third Law

Action Reaction

What do you predict will happen when the air is released from the balloon? Why?

string

Let’s Observe….

air goes this way!

string

Newton’s 3rd Law of Motion

ACTION - Air released

string

REACTION - Balloon moved

Newton’s 3rd Law of Motion states:

When one object exerts a f____ on a second object, the second object exerts a f____ on the first that is e____ in size and o______ in direction.

orce

orcequal pposit

e

For every A_____ there is an equal and opposite R______!

Newton’s 3rd Law…Sum it up…

ction eaction

QUESTION???

Is it possible for you to touch without being touched? Think about it….

Remember…forces come in pairs.

Billy-Bob shoots a hunting gun.Can you identify the action?

Can you identify the reaction?

ACTION: Bullet exiting gunREACTION: Gun pushing Billy-Bob back

Sarah is on ice skates and she pushes against a wall.

Can you identify the action? Can you identify the reaction?

ACTION: Pushing on wallREACTION: Wall pushing back

Here is a water rocket.Can you identify the action?

Can you identify the reaction?

ACTION: Pressurized water exiting the rocket

REACTION: water rocket shooting upward

Jimmy lifts his weights.Can you identify the action?

Can you identify the reaction?

ACTION: Pushing up on weightsREACTION: Weights pushing down

Charlie hit a baseball.Can you identify the action?

Can you identify the reaction?

ACTION: Bat hitting ballREACTION: Ball hitting bat and the ball accelerating