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Homework exercises on work against a resistive force for a Physical Science course. Also refer to Physics, friction, energy, springs, gravity, WBT, education, distance learning, Ron Kurtus, School for Champions. Copyright © Restrictions

Work and Machines - Homework Answers

After you have completed the Work and Machines Homework, you can refer to these answers. Although it is better to have known the answer from your reading, the process of writing the correct answer on your homework sheet will help you remember the concepts.

Resistive Forces

1. Why are some things more difficult to move than others?

There are resistive forces such as friction and gravity..

2. What are some examples of resistive forces?

Friction and gravity.

3. What is friction?

A force of resistance.

4. How do you increase friction?

Increase pressure or increase coefficient of friction.

5. How do you decrease friction?

Lubricate materials.

6. When would you want to increase friction?

When you want to stop something..

7. What is the major cause of air or water resistance?

You must push the air or water out of the way.

8. How do you decrease air resistance?

Streamline the object.

9. If you throw a ball up in the air, gravity causes it to slow down. When does its velocity reach zero?

At the top, just before it starts to come down. Also when it comes to rest on the ground.

Work Against a Force

1. What is the definition of work?

Force against a resistance times the distance traveled..

2. How do you measure the work against the force of friction?

Measure the force and the distance traveled.

3. What is the work against the resistance of gravity?

Force times height.

Machines

1. What is a purpose of a machine?

To make work easier or even possible.

2. One side of a teeter-totter (lever) is 8 feet long and the other side is 4 feet long. On which side would you sit, with a child on the other side?

The short side.

Where can you go from here?