Balanced and Unbalanced Forces

Balanced and Unbalanced Forces

8th Grade Science

Poll

Do you know what a force is?

• Yes

• No

• Maybe

What is a force?

A force is a push or pull of an object that leads to a change in position.

This means that a force has both strength and direction.

A force is measured in Newtons and is represented by N.

Open Ended

Give an example of a force.

Forces can be

• Balanced

• Unbalanced

A force is balanced when:

• The same amount of energy is applied to opposite sides of the object

• The object DOES NOT have a change in motion or direction

Example of a Balanced Force

Example of Balanced Force

Tug of War is a well known example for forces.

A force is unbalanced when:

• two forces of different values are on opposing sides of an object

• There is a change in motion or direction of an object.

Due to the unbalanced forces, the object is moving in the direction of the larger force

Here are more examples of unbalanced forces

Net Force

Net Force is the sum of all opposing forces acting on an object. This means that figuring out the net force of an object will involve addition.

This means that for a balanced force the net force would be equal to zero.

An unbalanced force would have a net force that could be either positive or negative.

Poll

Can an object that is exhibiting balanced force still be in motion?

• Yes

• No

The answer is yes!

According to Sir Isaac Newton's First Law of Motion ( Also referred to as The Law of Inertia) states that an object at rest will stay at rest, or an object in motion will stay in motion until an opposing force acts upon it. This means that the object will be showing constant speed until another force acts upon it.

Practice Time!

Lets see what you know!

Multiple Choice

Are the forces acting on the rope balanced or unbalanced?

• Balanced
• Unbalanced

Multiple Choice

These forces are...

• Balanced

• Unbalanced

Multiple Choice

How will this object move? 

• It won't move. 
• It will move to the right. 
• It will move to the left. 
• It will move up. 

Multiple Choice

Why doesn't the ping-pong ball just shoot up to the ceiling?

• air pressure

• force of gravity

• force of air above it

• trick ping-pong ball

Multiple Choice

What is the net force?

• 40 N left
• 0 N Balalnced
• 400 N right
• 40 N right

Multiple Choice

Which could be an example of a balanced force?

• An asteroid moving at a constant speed through space 
• A car accelerating from a stop sign
• A box of dishes falling from a counter 
• A rocket taking off 

Multiple Choice

Which could be an example of an unbalanced force?

• A plate sitting on a dining table
• A ball at the top of a hill that is not moving
• Earth orbiting the Sun 
• A baseball that has been thrown to home plate.

Multiple Choice

A wheeled cart is moving to the right at a constant speed.  Two forces of equal magnitude are acting upon the cart. Which of the following best describes the forces and motion of the cart?

• Balanced Forces, Constant Speed
• Balanced Forces, Acceleration
• Unbalanced Forces, Constant Speed
• Unbalanced Forces, Acceleration

Multiple Choice

You and your dad are moving the couch from one side to another. Your dad pushes with a force of 35 N to the right and you push with a force of 25 N right. What is the net force on the couch?

• 60 N right
• 10 N left
• 60 n right
• 50 N left

Multiple Choice

A force has both strength and ________.

• power
• direction
• color
• balance