A force is an interaction between 2 objects involving a push or a pull.

Forces are vectors - they are drawn as arrows (have size and direction).

The units of measure for force is: Newtons

Draw an object being pushed with a force vector!

5 Newtons

Unbalanced and Balanced ForcesUnbalanced forces cause objects to

accelerate (like your object being pushed).

Balanced forces means NO acceleration. Can you think of an example of when forces are

balanced and do NOT cause an object to accelerate?

Balanced Force = No acceleration

Unbalanced Force = Acceleration

Force or Action Force Vector Prediction

(draw in Force Vectors )

Real-World Example

(List an example of each

force or action in real-life)

Squeezing/Compression

Stretching/Tension

Bending

Sliding/Shearing

Twisting/Torsion

Crumple a paper

Pull on a rubber band

Bend a straw

Slide down a hill, earthquake

Open a soda bottle, ringing out a towel

It Matters….

Inertia is a property of matter

All objects are matter

• They are made of atoms

• Stuff you can see or touch!

Anything made of matter (solid,

liquid, gas) is an “object”.

The Greeks thought there were two types of motion:

Natural motion - what an object “naturally wants to do”

Violent motion - what an object has to be forced to do

The Greeks did not get the idea of friction!

Realized the role of friction by rolling marbles down ramps and sliding objects across tables.

If left to themselves,moving objects do NOT slow down.

Without friction objects keep the same velocity!

No Acceleration!

INERTIA!

Objects

Tablecloth Video

Why do the items in the video

stay in the same place when

the tablecloth is pulled away?

Newton’s First Law says that objects do not

accelerate on their own – they need an

unbalanced force to accelerate.

This property of matter, which causes objects to

resist acceleration, has been named “inertia”.

The bigger the mass of an object the harder to

accelerate (boulder vs. rock)

So the bigger the mass, then the greater the inertia

Bigger Mass Greater Inertia Harder to accelerate

Inertia Activity

Pick 5 objects in the room and label

them from greatest inertia to least

inertia.

Explain in 10-20 words what inertia

means.

If an object is at rest or moving at a constant velocity it is at equilibrium(happy).

Static Equilibrium

Object at rest

Forces are balanced

(no acceleration)

Dynamic Equilibrium

Object moving at a

constant velocity

Forces are balanced

(no acceleration)

Static (At Rest) Equilibrium

Velocity is zero

Examples:

Weighing yourself on a set of scales

Computer setting on a table

Car parked on an incline

Table pushing up

Weight down

Weight downWeight down

Scales pushing up

Ramp pushing upFriction

Dynamic EquilibriumVelocity is constant

Examples:

Driving at constant velocity

Force from road

Weight down

Friction

Normal up

Weight downAir resistance

Terminal velocity in parachuting

Inertia Demo

What do you think will happen to the

cart and tennis ball when it gets to the

bottom of the ramp?

Make a prediction and explain your

reasoning.

Newton's 1st Law

and Mr. Ganey Driving

Because of inertia, objects (including

Mr. Ganey) resist changes in their

motion. If a car is going 40 mi/hr and is

stopped by a brick wall, Mr. Ganey

keeps moving at 40 mi/hr.

This is why we wear seat belts.

Extensions: Complete Chapter

2.1 Reading Section questions 1-3

page 47 (answer on listening guide)

Begin Chapter 2 Packet

Force Vector Fun!

Define Mass and Weight

Mass – the amount of stuff in an object

the quantity of matter (atoms) in an object

the measurement of the inertia

measured in kilograms (kg)

Weight – how hard an object pushes down

Is a measure of the force of gravity on an object Weight = Mass Acceleration of gravity

W = mg

F = ma

measured in Newtons (N)

Your Weight on Other Worlds

Acceleration due to gravity on the Moon is weaker than on Earth. Gravitational acceleration on Earth = 9.8 m/s2

Gravitational acceleration on Moon = 1.6 m/s2

So, you would weigh less on the Moon than on Earth.

But you would have the same mass on both the Earth and Moon! You are still you – you are still made up of the same stuff; the same amount of matter (atoms).

Weight depends on Gravity!

Your mass does NOT depend on where you are. (e.g. Earth, Moon, or space). Mass is universal – the same everywhere!

In space you are “weightless” but not “massless”.

W = mg

So if gravity is weak you are basically weightless and if gravity is strong you weigh a lot. Let’s try figuring out our weight on different worlds.

Calculate

Weight = mass x gravitational acceleration

Newtons = kg x little g

Earth g = 9.8 m/s2

Moon g = 1.6 m/s2

A soccer player has a mass of 45 kg.

Calculate the soccer player’s weight on

Earth and on the Moon.

Newton’s Second Law

Interactive

Check for Understanding

The same force is applied to each box.

If box 1 has a smaller mass than box 2,

which one will have the greater

acceleration?

Circle your answer.

F F

Box 1 Box 2

2nd Law (F = ma)

How much force is needed to accelerate a 1400 kilogram car 2 m/s2?

Write the formula

F = m x a

Fill in given numbers and units

F = 1400 kg x 2 m/s2

Solve for the unknown

2800 kg- m/s2 or 2800N

Extension Work

If not completed: Complete Chapter 2.1 Reading

Section questions 1-3 page 47

Record answers on listening guide

Complete Chapter 2.2 Reading Section questions 1-3 page 55

Record answers on listening guide

Chapter 2 Packet Complete 2.1, 2.2, Math Support, and Math Practice

Grab a laptop and try the -

Rocket Video

Which of Newton’s

Laws explains how

a rocket takes-off?

Who is considered

the father of the

modern-day rocket?

All forces come in pairs!

For every action force there

is an equal and opposite

reaction force

Action-Reaction Force Pairs Ever sat down on the floor?

Of course you have!

What do you do to stand back up?

You push down on the ground and

it pushes you back up.

The Earth has a lot of inertia (large

mass) so it does not accelerate

very much.

You have a less inertia (smaller

mass) so you accelerate upwards

quite easily.

Try out some

triceps push-ups

on your chair!

Action force

The Weight of your body

pushes down on the chair.

Gravity is pulling the mass of

your body downward!

We call this downward force

your weight.

Reaction force

The chair pushes back up

on your body.

That’s why it can hurt to sit in

a chair a long time!

Newton's Third Law

Identifying Force Pairs

Can you describe the

action and reaction

forces?

Action force:

Bat pushes ball

Reaction force:

Ball pushes bat

Ball moves forward and

bat moves backward.

Action force:

A car has wheels

which spin backwards.

As the wheels spin

backwards, they grip

the road and push on

the road backwards.

Reaction force:

The road then pushes

the car forward.

Identifying Force Pairs

Car moves forward as the

tires push backwards on

the road.

Identifying Force Pairs

Flying gracefully through the air, birds depend on Newton’s third law of motion.

Action force: Birds push down on

the air with their wings

Reaction force: The air pushes their

wings up and gives them lift

Identifying Force Pairs

Action force: A fish uses its fins to

push water backwards.

Reaction force: The water pushes the

fish forwards.

These action-reaction forces let the fish swim!

Identifying Force Pairs

3-2-1 Blast-off!Gases get pushed down and the

rocket gets pushed up!

Various fuels are burned in the engine, producing hot gases.

Action force: The hot gases slide

against the inside tube of the rocket and are pushed out of the bottom of the tube.

Reaction force:

As the gases move downward, the rocket the gases push the rocket upwards. Inertia and F = ma

As the rocket burns fuel (reduces

mass) it accelerates more easily!

Try this out at home!

Astronauts in Space

Remember everything is either matter, energy, or

nothingness!

The astronauts working on the space station have a

serious problem when they need to move around in

space: There is nothing to push on.

The solution is to throw something in the opposite

direction you want to move.

This works because all forces always come in pairs.

Astronauts in Space Video

Challenge Question

How does a jellyfish move up and down in the water?

Illustrate your explanation with vectors. Hint: Look at page 57 in

your textbook.

Think about Newton’s Third Law! Make sure to draw action-

reaction force vectors!

Extension Work If not completed:

Complete Chapter 2.1 Reading Section questions 1-3 page 47

Record answers on listening guide

Complete Chapter 2.2 Reading Section questions 1-3 page 55

Record answers on listening guide

Complete Chapter 2.3 Reading Review questions 1-3 page 61

Record answer on listening guide

Chapter 2 Packet Complete 2.1, 2.2, Math Support, Math Practice, and 2.3.

Grab a laptop and try the -

Create a poster with an illustration and text describing the motion of an object

Top Posters will earn Bonus Points for your class period and be used as classroom

decoration!

• Can you explain Newton’s

Laws to your family using a

balloon?

• Think about Inertia, F=ma,

and action-reaction force

pairs.

Momentum is what Newton called the

“quantity of motion” of an object.

Momentum

So What’s Momentum ?

• Momentum is the measure of mass in motion

• Momentum = mass x velocity

• This can be abbreviated to : . momentum = mv

• Or, if direction is not an important factor : . . momentum = mass x speed

• So, a really slow moving truck and an extremely fast roller skate can have the same momentum.

Question :

• Under what circumstances would the roller skate

and the truck have the same momentum?

• If the roller skate moves really fast and the truck

moves really slow, then they could have the

same momentum. This is due to the fact that

momentum is the mass of an object times the

velocity it is travelling.

• A 1000 kg truck moving at 0.01 m/s has the same

momentum as a 1 kg skate moving at 10 m/s.

Both have a momentum of 10 kg m/s.

• (1000kg x .01m/s = 1kg x 10m/s = 10 kg x m/s )

1000 kg1 kg .01 m/sec10 m/sec

• ELASTIC COLLISIONS – objects bounce away

• INELASTIC COLLISIONS – objects stick together

Momentum transfers from one

object to another as they bounce

off each other

Collisions on an air track

Momentum Interactive

Copy the data table above into your notebook

Predict: When two objects collide, what will happen to their

motion?

Momentum Table

Mass - A (kg)Vi of 1 m/s

Collides with

Mass – B (kg)Vi of 0 m/s

Prediction Observed Result

1.0 kg 0.7 kg

1.0 kg 1.0 kg

1.0 kg 1.4 kg

Momentum Interactive

Conservation of MomentumMomentum is conserved if there are no outside forces when objects collide.

The only forces present during the collision are the action-reaction force pairs.

Extension Work Read as needed through Chapter 2.4

Complete the section questions 1-3 on

page 69 in your science notebook

Finish the Listening Guide and

Chapter 2 section questions

Complete Newton’s Laws Tree Map

Complete Chapter 2 Packet

All pages

Grab a laptop and try the

-

Create a poster with an illustration and text describing the motion of an object

Top Posters will earn Bonus Points for your class period and be used as classroom

decoration!

Independent Work Day

Complete Newton’s Laws Listening Guide and Chapter 2 sections questions

Newton’s Laws Tree Map

Complete Chapter 2 Packet Create a poster with an

illustration and text describing the motion of an object

Top Posters will earn Bonus Points for your

class period and be used as classroom decoration!

Go to the virtual lab and select some of the other tabs

Investigate these concepts

• Isaac Newton goes Skiing (Lab Book pages 222-225)

• Read, chunk, and create a SMART summary in your notebook.