Introduces work and shows calculations of the work done in several situations.

1. Preview
Section 1 Work
Section 2 Energy
Section 3 Conservation of Energy
Section 4 Power
Mr. Thompson's Physics Class

2. What do you think?

List five examples of things you have done in the last year that
you would consider work.

Based on these examples, how do you define work?
Mr. Thompson's Physics Class

3. 
Workthe force (F) times the
In physics, work is the magnitude of
magnitude of the displacement (d) in the same direction as the
force.

W = Fd

What are the SI units for work?
− Force units (N) x distance units (m)
− N•m are also called joules (J).

How much work is 1 joule?
− Lift an apple weighing about 1 N from the floor to the desk, a
distance of about 1 m.
Mr. Thompson's Physics Class

4. 
Workthe force (F) times the
In physics, work is the magnitude of
magnitude of the displacement (d) in the same direction as the
force.

W = Fd

What are the SI units for work?
− Force units (N) x distance units (m)
− N•m are also called joules (J).

How much work is 1 joule?
− Lift an apple weighing about 1 N from the floor to the desk, a
distance of about 1 m.
Mr. Thompson's Physics Class

5. Work and Energy Section 1
Work
• Pushing this car is work because F
and d are in the same direction.
• Why aren’t the following tasks
considered work?
– A student holds a heavy chair at arm’s
length for several minutes.
– A student carries a bucket of water along
a horizontal path while walking at a
constant velocity.
Mr. Thompson's Physics Class
© Houghton Mifflin Harcourt Publishing Company

6. Work and Energy Section 1
Work
How would you calculate the work in this case?
What is the component of F in the direction of d?
• F cos 
– If the angle is 90°, what is the component
of F in the direction of d?
• F cos 90° = 0
– If the angle is 0°, what is the component of
F in the direction of d?
• F cos 0° = F
Mr. Thompson's Physics Class
© Houghton Mifflin Harcourt Publishing Company

7. Work
Mr. Thompson's Physics Class

8. Work is a ScalarWork can be

positive or
negative but
does not have a
direction.

What is the
angle between F
and d in each
case?
Mr. Thompson's Physics Class

9. Classroom Practice Problem

A 20.0 kg suitcase is raised 3.0 m above a
platform. How much work is done on the
suitcase?

Answer: 5.9 x 102 J or 590 J
Mr. Thompson's Physics Class

10. Now what do you think?

Based on the physics definition, list
five examples of things you have
done in the last year that you would
consider work.
Mr. Thompson's Physics Class