Lesson 1.4: What is Work?

What does work mean to you?  You most likely use the term work to mean something you do to accomplish something.  Cutting the lawn, doing a job, even reading this lesson might be considered work.  In this science course work means something more specific. 

Read What is Work? on page 132 and You Know You are Working When on page 133. Then, answer the following questions.

Question 1. What is the definition of force?

Question 2. What is the unit of force?  What is the symbol used to represent this unit?

Question 3. When is work done?

Question 4. What are the two units of work described in the reading?

Question 5. What is the formula used to calculate work?  What do the symbols in the formula for work mean?

Question 6. The diagrams on page 133 show a person in two situations, downhill and uphill.  If the person was riding on a flat road, would he be doing any work? 

Question 7. A person is standing and holding an armful of books.  Is work being done?

Question 8. A person lifts a pile of books from the floor onto a desk.  Is work being done?  

 

Check your answers with those that follow.

 

 

 

 

 

 

 

 

 

 

 

Answers to Questions:

Question 1. What is the definition of force?

Force is a push or a pull.

Question 2. What is the unit of force?  What is the symbol used to represent this unit?

The unit of force is a newton.  The symbol for the newton is N.

Question 3. When is work done?

In this science course, work is done when a force moves an object.

Question 4. What are the two units of work described in the reading?

The first unit of work is a newton-metre (N·m).  The second unit of work is a joule (J).  They are equivalent units; 1.0 N·m  = 1.0 J

Question 5. What is the formula used to calculate work?  What do the symbols in the formula for work mean?

The formula used to calculate work is W = F·d

The symbols mean work is equal to force times distance.

Question 6. The diagrams on page 133 show a person in two situations, downhill and uphill.  If the person was riding on a flat road would he be doing any work?

It would depend on if he was exerting any force on the pedals.  If he was just coasting, then he would not be doing any work.  If he was pedaling and exerting force on the pedals, he would be doing work.

Question 7. A person is standing and holding an armful of books.  Is work being done?

According to the scientific definition, no work is being done because there is no motion.

Question 8. A person lifts a pile of books from the floor onto a desk.  Is work being done?

According to the scientific definition, work is being done because there is a force applied and there is motion in the direction of the force.

 


Click on the page forward to continue Lesson 1.