Friction

Friction

Multiple Choice

What force holds the planets in motion around the sun?

• Magnetic
• Electrical
• Gravitational
• Air Resistance

Multiple Choice

What does the strength of gravity between two objects depend upon?

• Mass & distance
• Mass & weight
• Gravity & inertia
• Inertia & mass

Multiple Choice

If the distance between the objects INCREASES and gets further apart, the gravity will:

• Increase

• decrease

• stay the same

Multiple Select

Check ALL the statements that are TRUE about gravitational pull!

• The smaller the mass the LESS gravitational pull an object has

• The closer objects are the LESS gravitational pull an object has

• The closer objects are the MORE gravity there is

• The larger the mass the MORE gravitational pull it has

Open Ended

An object has a mass og 4 kg.

What is its force?

Today it is COLD

• What's he doing with his hands?

• Why?

His hands will become warm after he rubs them together

The name of this force is friction

Friction

• Friction is a force that appears when two objects are in contact (touching)

• When the boy pushes the box, friction pushes back in the opposite direction

• The box will only move if the pushing force is greater than the friction force

If you push an object to the left, which direction does friction push?

Draw a diagram and include the force arrows

Why don't the cars slide down the hill?

The direction of friction

• Friction acts to oppose motion

• To draw the force arrow to represent friction, we need to first think: "which way is the object trying to move?"

• In this picture, the heavy box will try to move down the hill. Therefore, friction acts up the slope.

Open Ended

Give an examples of an object and a direction in which you want to move the object.

Then say in which direction friction will push.

Measuring friction

What is the name of the instrument in the picture?

• Use the forcemeter to measure the force of friction.

• If you pull the wooden block attached to the forcemeter, you will see the value of the force needed to move the block (measured in what unit???)

• If you made these changes to the experiment, what differences would you expect to see when you measure the force of friction?

• 
  

• Imagine the road is made of glass or ice. What would happen to the cars? Why?

• What differences between asphalt and glass may cause this?

• What does this tell you about friction?

Multiple Choice

On which surface will a toy car travel the furthest?

• Carpet
• Polished Wood
• Ice

Multiple Choice

This car is turning, but there’s a puddle of water in the road. Which diagram best shows how the puddle will affect the path of the car after it hits the puddle?

Multiple Choice

What does friction produce?

• light
• sound
• heat
• gravity

Multiple Choice

When most objects with smooth surfaces rub, there is less friction.

• True
• False

Multiple Choice

The rougher the surface, the faster an object will travel over the surface.

• True
• False

Multiple Choice

If you are unable to make it to the bottom of the slide, who won the tug of war between sliding friction and gravity?

• There is no winner, and your sad because you're stuck on a slide

• Gravity won

• Neither, its a tie

• Sliding friction won

Multiple Choice

True or False: objects that are smooth have LESS friction than objects that are rough

• TRUE

• FALSE

Multiple Choice

Friction _____________ motion

• Works in the same direction as

• Opposes

• Has not effect on

• Pulls against