Forces and motion

​Forces and motion

By Joshuah Powell

​How do you know?

Is this car moving?

How do you know?

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Is this car moving?

How fast? What direction?

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Are you moving?

Motion

An object is in motion if its position changes relative to another object

Reference Point and Relative motion

Reference point- a place or object to use for comparison to determine if something is in motion

Relative motion- motion can change based on the reference point

Categorize

Options (6)

The ground

the trees

the track

The roller coaster car

the person next to them

The seat

Organize these options into the right categories: a person on the ride is..

In motion relative to...

Stationary relative to..

a push or a pull

forces can be used to speed up, slow down, and change direction

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Force

units of force

Named after Sir Isaac Newton

newton

Fill in the Blanks

What is a force?

Fill in the Blanks

The units of force

Contact and non-contact forces

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​Types of Forces

When the objects actually touch one another

Examples include: push, pull, friction and normal force

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Contact forces

​The force that acts against gravity when a object is on a surface.

Always points perpendicular to the surface​

Normal Force

Acts against the motion of an object when making contact with a surface.
Always points the opposite direction of motion

Frictional force

Fill in the Blanks

The normal force always acts

to the surface an object is on

Multiple Choice

In which direction is friction acting on the runner sliding into second? (the runner is sliding to the left in the image)

• Toward the outfield (up)

• Toward second base (left)

• toward the infield (down)

• toward first base (right)

A force that occurs without the objects touching

Examples: Gravity and magnetism

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Non-contact forces

Non-contact, attractional force that acts between any two objects that have mass

Objects with a larger mass, pull with a larger gravitational force.

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Gravitational force

Multiple Choice

Why is the force of gravity weaker on the Moon than on Earth?

• A. because the Moon is very far from Earth

• B. because the Moon is colder than Earth

• C. because the Moon has less water than Earth

• D. because the Moon has a smaller mass than Earth

Weight is an objects mass times the gravitational acceleration

Relative based on where you are (you weigh less on the moon and more "on" Jupiter

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What is weight?

Earth has a gravitational acceleration of 9.8 m/s²

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What is weight?

Fill in the Blanks

If an object has a mass of 10 kg, what is the gravitational force acting on it?

Net- final result after deductions

Net force- final "total" force after forces are added

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Net Force

If the net force on an object is zero (balanced) that object will not change its motion.

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Balanced and unbalanced forces

If the net force is not zero (unbalanced) the object will change its motion.

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Balanced and unbalanced forces

Force diagrams are used to show all of the forces acting on an object

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Force Diagrams

The length of the arrow represents the magnitude (value) of the force

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Force Diagrams

The length of the arrow represents the magnitude (value) of the force

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Force Diagrams

Get out your whiteboards now

Draw a force diagram to show the forces acting on the divers.

Draw a force diagram to show the forces acting on the box.

Draw a force diagram to show the forces acting on the moon.

Multiple Choice

What is the FORCE? 

• 5 N
• 10 N
• 400 N
• 0 N

Multiple Choice

What is the net force?

• 5 N
• 45 N to the left
• 5 N to the right
• 45 N to the right

Multiple Choice

What is the net force?

• 17 N Right
• 3 N Right
• 3 N Left
• 17 N Left