Forces Day 4 - Balancing Forces

Balancing Forces

​How forces act in pairs.

Review - Net Forces

• When two or more forces act on an object, we need to combine them to find the net force.

• When the forces are in the same direction, we add.

• When the forces are in opposite directions, we subtract.

• A net force of 0 N means the forces are balanced, and motion will not change.

Multiple Choice

Forces are measured in ____.

• Newtons

• Meters

• Grams

Multiple Choice

If two forces are in the same direction, to find the net force, we ____.

• Add

• Subtract

Multiple Choice

If two forces are in opposite directions, to find the net force, we ____.

• Add

• Subtract

Multiple Choice

To find the net force, we should ____.

• Add

• Subtract

Multiple Choice

To find the net force, we should ____.

• Add

• Subtract

Multiple Choice

To find the net force, we should ____.

• Add

• Subtract

Multiple Choice

If an object's motion changes, the forces must be ____.

• Balanced

• Unbalanced

Drag and Drop

These forces push in ​​

Placeholder

directions.

To find the net force, we ​

Placeholder

.

The net force is ​ ​

Placeholder

.

This object ​

Placeholder

move.

Drag these tiles and drop them in the correct blank above

the same

subtract

add

0 N

will not

will

opposite

8 N

Drag and Drop

These forces push in ​​

Placeholder

directions.

To find the net force, we ​

Placeholder

.

The net force is ​

Placeholder

.

This object ​

Placeholder

move.

Drag these tiles and drop them in the correct blank above

the same

subtract

add

6 N

0 N

will not

will

opposite

Applied Forces

• An applied force is exerted by a person or object on to another object.

• Pushing or pulling

• Kicking or pedaling

• Throwing or catching

Multiple Choice

Pushing, pulling, throwing, and kicking are examples of ____ forces.

• Gravitational

• Applied

• Friction

Multiple Choice

Applied forces always involve____.

• Two objects

• One object and the Earth

• One object and the air

Multiple Choice

When Peter throws the ball, ____ exerts the applied force.

• Peter

• the ball

Multiple Choice

When Peter throws the ball, the applied force acts upon ____.

• Peter

• the ball

Multiple Choice

When Sandra pushes the shelf, ____ exerts the applied force.

• Sandra

• the shelf

Multiple Choice

When Sandra pushes the shelf, the applied force acts upon ____.

• Sandra

• the shelf

Dropdown

When horses pull the wagons, ​

Select answer

exerts the applied force, and it acts upon ​

Select answer

.

Dropdown

When Pat tosses the Frisbee, ​

Select answer

exerts the applied force, and it acts upon ​

Select answer

.

Gravity

• Gravity is a force that pulls objects towards each other.

• Heavier objects exert more gravity.

• Since Earth is always the heaviest object on Earth, gravity pulls things towards Earth's center.

  • Water is pulled down as rain.

  • Cooling magma is pulled down towards the core.

  • People who jump are pulled back to Earth's surface.

Dropdown

Gravity's force is best described as a ​

Select answer

,

so it moves objects ​

Select answer

Earth's center.

Multiple Choice

On Earth, gravity pulls everything towards Earth's center because ___.

• Gravity can only ever pull down.

• The magnets from the core cause the gravity.

• Nothing on Earth is heavier than Earth.

Multiple Select

Which two are examples of gravity's force?

(Pick 2!)

• Rain falls to Earth's surface

• A ball rolls across the grass.

• A ball falls from the hoop to the court.

• Rain rushes along the streets in a flood.

Multiple Choice

In almost every situation on Earth, gravity's force will pull ___.

• Up

• Down

• Left

• Right

Balancing Forces

• So far, we have mostly talked 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.

Normal Force

• The Normal Force is exerted by a surface against the object it is touching.

• Often, the normal force acts in the opposite direction of gravity.

Multiple Choice

The ____ force acts in the opposite direction to gravity.

• Friction

• Applied

• Normal

Multiple Choice

The Normal force acts in the ____ direction to gravity.

• Same

• Opposite

Multiple Choice

The Normal force acts in the opposite direction to ____.

• Gravity

• Motion

Multiple Choice

When we sit in a chair, gravity pulls us down, but the ___ force pushes us back up.

• Friction

• Normal

• Applied

Multiple Choice

When we put a book on the table, the ____ exerts the normal force.

• Table

• Book

Multiple Choice

When we put a book on the table, the normal force acts on the ____.

• Table

• Book

Multiple Choice

When we put a book on the table, the table exerts a normal force that pushes the book ____.

• Up

• Down

Dropdown

A soccer ball is still on the ground. ​

Select answer

is pulling the object down, but ​

Select answer

is pushing it back up.

Dropdown

In most cases on Earth, Gravity will pull the object ​

Select answer

, and the Normal force will push the object ​

Select answer

.

Friction

• Friction is also exerted by a surface on an object is it touching.

• Friction acts in the opposite direction of motion.

Multiple Choice

____ acts on objects on a surface, in the opposite direction to motion.

• Friction

• Normal Force

• Drag

Multiple Choice

Friction acts on objects ____, in the opposite direction to motion.

• In the air

• On a surface

Multiple Choice

Friction acts on objects on a surface, in the ____ direction to motion.

• Same

• Opposite

Multiple Choice

Friction acts on objects on a surface, in the opposite direction to ____.

• Motion

• Gravity

Multiple Choice

Zoe pushes a box on the ground to the left.

____ will push the box to the right.

• Normal Forces

• Gravity

• Friction

Multiple Choice

Darius pulls his book across the table to his right.

Friction will pull his book ____.

• Up

• Down

• Left

• Right

Multiple Choice

Steve hits a hockey puck across the ice to the left.

Friction will push the puck ____.

• Up

• Down

• Left

• Right

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

Drag

• Drag is exerted by the air onto an object it is touching.

• Often, drag acts in the opposite direction of motion.

Multiple Choice

____ acts on objects in the air, in the opposite direction to motion.

• Normal

• Drag

• Friction

Multiple Choice

Drag acts on objects ____, in the opposite direction to motion.

• On a surface

• In the air

Multiple Choice

Drag acts on objects in the air, in the ____ direction to motion.

• Same

• Opposite

Multiple Choice

Drag acts on objects in the air, in the opposite direction to ____.

• Motion

• Gravity

Dropdown

Drag acts on objects ​

Select answer

, but friction acts on objects ​

Select answer

.

Both drag and friction act opposite to ​

Select answer

.

Multiple Choice

A football is flying through the air. Which force is pushing against its motion?

• Friction

• Drag

Multiple Choice

A skateboard is rolling along the sidewalk. Which force is pushing against its motion?

• Friction

• Drag

Multiple Choice

A plane is driving along the runway. Which force is pushing against its motion?

• Friction

• Drag

Multiple Choice

A plane is flying through the sky. Which force is pushing against its motion?

• Friction

• Drag

Multiple Choice

A plane is flying to the left. Drag is pushing ____.

• Up

• Down

• Left

• Right

Multiple Choice

A parachuter is flying downwards. Drag will pull the parachuter ____.

• Up

• Down

• Left

• Right

Labelling

Match the force to the letters.

Drag labels to their correct position on the image

Normal

Applied

Drag

Friction

Gravity

Open Ended

"Friction and drag are similar because ____.

Friction and drag are different because ____."