Write the type of KINETIC FRICTION SHOWN BELOW.

Friction: A Force That Opposes MotionWhat do you know about friction?

TASK

Follow along as we review the answers to the friction questions.

ANSWER THE QUESTIONS ON THE PAPER THAT WAS PASSED OUT TO YOU.

In your own words, write a definition for the term net force.

A combination of all forces that act on an object.

In your own words, write a definition for the term friction.

Friction is a force between any two surfaces, that opposes motion.

This type of force causes a change in the speed or direction of an object.

Unbalanced force

Which direction is the force of friction pushing against the block?

Why is it easier to slip when there is water on the floor?

a) The water is a lubricant that when spilled, fills in the hills and valleys on the floor and reduces friction between your feet and the floor

Forces are measured in these units.

Newtons

Explain why friction occurs.

Friction occurs because surfaces are covered with microscopic “hills and valleys” that stick to each other when they come in contact.

Friction is caused when microscopic hills and valleys of objects rub together:

How does the roughness of surfaces that are touching affect the friction between surfaces?Rough Surfaces have more hills and valleys that increase the force of friction. Smooth surfaces have less hills and valleys, therefore less friction occurs.

Which will have more friction?

These surfaces will have more friction because they have larger hills and valleys than the other picture. This means they are more rough.

Describe how the amount of force pushing two surfaces together affects friction.

If the force pushing the two surfaces together is great, the hills and valleys are in closer contact and friction increases.

More Force = More Friction

Name two ways in which friction can be increased.

Make a surface rougher

Push surfaces together harder

List the two types of friction, and give an example of each.

Kinetic- sliding a book across the tabletop

Static- pushing a piece of furniture and it not moving.

List the three types of Kinetic Friction and give an example of each:

Sliding Kinetic Friction- moving a book across a desk, applying brakes in a car, scratching your arm

Rolling Kinetic Friction- wheels of a bike, toy car, trains on a track

Fluid Kinetic Friction- oil lubricating parts on a plane, car, or bike, water flowing through a hose

Forces

1.The forces shown above are PUSHING / PULLING/ PUSHING AND PULLING forces. 2. The forces shown above are WORKING TOGETHER / OPPOSITE FORCES. 3. The forces are EQUAL / NOT EQUAL. 4. The forces DO / DO NOT balance each other. 5. There IS / IS NO motion.6. The net force is __________________ in _________________ (direction).

Two young girls are fighting over a present. One is pushing is with a force of 10N to the right and the other is pushing with a force of 50 N to the left. Use the picture below to answer the questions that follow.

Forces

1.The forces shown above are PUSHING / PULLING/ PUSHING AND PULLING forces. 2. The forces shown above are WORKING TOGETHER / OPPOSITE FORCES. 3. The forces are EQUAL / NOT EQUAL. 4. The forces DO / DO NOT balance each other. 5. There IS / IS NO motion.6. The net force is __________________ in _________________ (direction).

Two children are moving their wagon across the street. One is pulling the wagon to the left with a force of 100N and the other is pushing the wagon with a force of 100 N to the left. Use the picture below to answer the questions that follow.