Newton's First Law

Newton's First Law

Or "The Law of Inertia"

Review - Balancing Forces

• We began the unit talking about applied forces and gravity.

• Many other forces can affect an object's motion, often by acting in the opposite direction.

• Normal forces push back against gravity.

• Friction and drag push back against motion.

Labelling

Match the force to the letters.

Drag labels to their correct position on the image

Drag

Normal

Applied

Friction

Gravity

Dropdown

A soccer ball is still on the ground. ​

Select answer

is pulling the object down, but ​

Select answer

is pushing it back up.

Drag and Drop

When soccer legend Megan Rapinoe kicks the ball,

her ​

Placeholder

pushes the object right, but ​

Placeholder

pushes the object left.

Drag these tiles and drop them in the correct blank above

applied force

friction

gravity

normal force

Dropdown

Drag acts on objects ​

Select answer

, but friction acts on objects ​

Select answer

.

Both drag and friction act opposite to ​

Select answer

.

Dropdown

The Normal Force always acts opposite to ​

Select answer

, while Drag and Friction act opposite to ​

Select answer

.

Categorize

Options (12)

Opposite to Gravity

On the ground

In the air

A ball sitting on a shelf

A ball rolling on the groun

A ball flying through the air

A plane parked on the runway

A plane driving on the runway

A plane flying through the clouds

A kite caught in a tree

A kite dragged along the sidewalk

A kite blown by the wind

Organize these options into the right categories

Normal

Friction

Drag

Dropdown

When we sit in a chair, ​

Select answer

pulls us down, but the ​

Select answer

force pushes us back up.

Review - Why care about balancing forces?

• When two or more forces act on an object, they combine to make a net force.

• When the net force = 0 N, the forces are balanced, and motion will not change.

Multiple Choice

Darius pulls his book across the table to his right.

Friction will pull his book ____.

• Up

• Down

• Left

• Right

Multiple Choice

Which direction will the object move?

• Left

• Right

• It won't move

Multiple Choice

Which direction will the object move?

• Left

• Right

• It won't move

Newton's First Law

• Objects at rest will stay at rest unless acted upon by an unbalanced force.

• Objects in motion will continue at the same speed and in the same direction, unless acted upon by an unbalanced force.

Multiple Choice

What kind of forces can change the motion of an object?

• Balanced forces

• Unbalanced forces

Multiple Choice

If the net force = 0 N, the forces are ____.

• Balanced

• Unbalanced

Multiple Choice

If the net force = 0 N, motion ____.

• Will stop

• Will not change

Multiple Choice

An unbalanced force is needed to make an object ___.

• Speed up

• Slow down

• Change direction

• All of these

Dropdown

An object at rest will stay ​

Select answer

, but an object in motion will stay ​

Select answer

, unless acted upon by ​

Select answer

.

Multiple Choice

A ball is sitting still on the grass. Gravity is pulling it down, but the normal force is pushing it up, and the net force is 0 N. What will happen to the ball?

• It will stay still

• It will start to move

Multiple Choice

A ball is rolling on the grass. The applied force of the kick was 5 N left,

and the force of friction is 5 N right.

What will happen to the ball?

• It will keep moving at a constant speed.

• It will speed up.

• It will slow down and then stop.

Multiple Choice

A ball is rolling on the grass. The applied force of the kick was 10 N left, and the force of friction is 5 N right.

What will happen to the ball?

• It will keep moving at a constant speed.

• It will speed up.

• It will slow down and then stop.

Multiple Choice

A ball is rolling on the grass. The applied force of the kick was 5 N left, and the force of friction is 10 N right.

What will happen to the ball?

• It will keep moving at a constant speed.

• It will speed up.

• It will slow down and then stop.

Multiple Choice

A parachuter is falling through the air. Gravity pulls at 10 N down, but drag pulls at 5 N up.

What will happen?

• The parachuter will fall at a constant speed

• The parachuter will fall faster

• The parachuter will fall slower

Multiple Choice

A parachuter is falling through the air. Gravity pulls at 10 N down, but drag pulls at 10 N up.

What will happen?

• The parachuter will fall at a constant speed

• The parachuter will fall faster

• The parachuter will fall slower

Multiple Choice

A parachuter is falling through the air. Gravity pulls at 10 N down, but drag pulls at 20 N up.

What will happen?

• The parachuter will fall at a constant speed

• The parachuter will fall faster

• The parachuter will fall slower

Open Ended

Look at the forces acting on the basketball.

Do you think it will speed up, slow down, or fall at the same speed?

"I predict the ball will ___ because ____."

Law of Inertia

• Newton's first law is also called the Law of Inertia.

• Inertia means an object will keep doing what it was doing.

• An object that was moving will keep moving. An object that is still will stay still.

Multiple Choice

Newton's first law is also called the Law of ___.

• Forces

• Inertia

• the Land

Multiple Choice

___ means an object will keep doing what it was doing.

• Friction

• Gravity

• Inertia

Multiple Choice

Because a still object has inertia, we need ____ to make it move.

• An unbalanced force

• A balanced force

• To convince it to move

Multiple Choice

You are the passenger in a car. When the car stops suddenly, you keep moving forward because of ____.

• Gravity

• Inertia

• The normal force

Multiple Choice

You are the passenger in a moving car. How did the driver stop the car?

• By applying force to the brakes

• By wishing the car would stop

• By waiting for the car to stop on its own

Multiple Choice

Inertia keeps you moving when the car stops suddenly, unless a ____ provides an unbalanced force to stop your motion.

• Gust of wind

• Seat belt

• Helmet

Inertia and Mass

• As mass increases, so does inertia.

• It takes a stronger unbalanced force to stop a big moving vehicle than a small one.

• It takes a stronger unbalanced force to get a large shelf moving than a small one.

Multiple Choice

Which object has more inertia?

• A real fire truck

• A toy fire truck

Multiple Choice

Which object has more inertia?

• A kindergarten student

• A teacher

Multiple Choice

Which object will you need more force to stop?

• A car

• A skateboard

Multiple Choice

Which object will you need to push harder to move?

• An empty bookshelf

• A full bookshelf

Open Ended

"It is important to wear a seat belt in the car because ___."