Describing Forces and Motion

Chapter 10

Forces & Motion

Lesson 1&2

Big Question: How do forces affect motion?

Multiple Choice

What is motion?

• the action or process of moving or being moved.

• When nothing is acting on an object

• When something stays in the same place.

• When an object is balanced.

What is Motion?

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

A reference point is what appears to be remaining still compared to the object you are observing.

Describing Motion

Motion can be described by distance, speed, displacement, and velocity, where displacement and velocity also include direction.

Multiple Choice

Which of the following defines motion?

• Change in time.

• A change in position.

• A change in size.

• A balanced force.

When you describe motion in science...

you explain it with a magnitude and a direction.

This is known as a vector quantity.

Multiple Choice

If you describe something's magnitude and direction, this is known as a...

• scalar quantity

• vector quantity

• reference point

• motion

So, what is acceleration?

In science acceleration refers to increase speed, decreasing speed, or changing direction.

Multiple Select

An airplane is circling overhead at a constant unchanging speed. It is...

(Check all that apply.)

• moving

• balanced

• sitting still

• accelerating

Multiple Select

A car is going down a straight highway at a constant speed of 55mph. It is ... (Check all that apply.)

• Accelerating

• Sitting still

• In motion

• NOT accelerating

Multiple Select

A semi squeals to a stop in about 3 seconds after slamming on the brakes. That semi was...(Check all that apply.)

• NOT accelerating

• accelerating

• moving

• sitting still

Multiple Choice

Is this yellow car accelerating?

• No, it isn't speeding up.

• No, it is traveling at a continuous speed.

• Yes, it is constantly changing direction.

• Yes, because it is moving.

There is a simple formula for Acceleration.

Acceleration = Change in Velocity /Change in time.

What causes something to move or acclerate?

Forces cause things to move!

A force is a push or a pull!

Like acceleration, a force is described by its magnitude and its direction. It is a vector quantity.

Multiple Choice

Which direction do you think this box will move?

• up

• down

• to the right

• to the left

Forces are measured in Newtons. (N)

This represents the magnitude of the force.

(A kilogram is equal to about 2 pounds.)

So how do forces make something move?

When forces are NOT balanced an object moves.

If the forces are balanced an object doesn't move.

This means no acceleration!

​NO MOVEMENT!

Multiple Choice

Are the forces on this object balanced?

• Yes, they are balanced!

• No, they are not balanced!

The bigger the arrow on a force drawing the bigger the force.

The magnitude of the force is represented by the size of the arrows!

Multiple Choice

Which direction will this box move?

• up

• down

• left

• right

Multiple Choice

Which direction will this box move?

• left

• right

• up

• down

Multiple Choice

Which direction will this box move?

• down

• left

• diagonal to the right

• up

What is a net force?

This is the combinations of all the forces acting on an object.

* If the arrows point the same direction you add the forces.

* If the arrows point the opposite directions you subtract!

Multiple Choice

Would you add or subtract these forces?

• add

• subtract

Multiple Choice

Would you add or subtract these forces?

• add

• subtract

Whatever the answer is you get from this is known as your "NET FORCE"

Let's try a force diagram problem!

What would the "NET FORCE" be for this force drawing?

Multiple Choice

What is the net force?

• 5N up

• 0 N

• 5 N Down

• 0 N to the Right

Multiple Choice

What is the Net Force?

• 2 N up

• 8 N right

• 2 N right

• 0 N

• 10 N up

Multiple Choice

What is the Net Force?

• 0 N

• 14 N out

• 10 N left

• 4 N up

• 0 N down

Multiple Choice

What is the Net Force?

• 200 N up

• 350 N left

• 400 N down

• 0 N

Poll

Click on what applies to you!

• I understand Motion & acceleration

• I understand Force Drawings and Net Force

• I don't understand Force or Net Force!

• I don't understand Motion!

• I don't understand Acceleration