Work involves applying a force over a distance. In physics, work is defined by the formula W=Fd, where W is work, F is force, and d is distance. Examples of work include moving an object with a force of one newton over a distance of one meter, which equals one joule of work. A joule is the standard unit used to measure work. Machines like simple machines can help us do work by multiplying the force applied.

1. Work
Chapter 5.1

2. What is work?
• You work on math problems.
• You go to work.
• Making a sandwich is work.
• Taking out the trash is too much
work.
• Doing your homework is work.
• What machines help us work?

3. In physics, work is:
• *Work is a formula: W=Fd
• *W= Work; F= Force; d= distance
• *Example:
• *Moving an object with a force of one
newton for a distance of one meter=
one joule of work
• *A joule is a unit that measures work

4. Force (N)
Work (joules) W=Fxd
Distance (m)

5. Brainstorm using a circle map:
1. In the Center write: Work
2. In the circle write types of simple machines
3. In the frame of reference write down what
work these machines do

6. Input and Output
• *Input = how much force you put
into doing work
• *Output = how much work was
done
• *The work output can never
exceed the work input!

7. Work:

9. Efficiency
• *Efficiency is the fraction of
incoming energy that goes into a
process.
Examples: Fuel mileage,
appliances and energy efficiency

10. *Efficiency
• What does it mean to be efficient?
• *In a very efficient machine, all or
most of the work input becomes work
output
• In other words…if five joules of work
was used to lift a box, the box would
move the equivalent of five joules
output- nothing was wasted.

11. What about friction?
• *In the real world- Work Output is
always less than work input.
– WHY?
• *Forces like friction use up some of
the input work
– Example: wheel turning on an axle can
get very hot…when the wheel gets hot
some of that input work is being
converted to heat.

12. Friction

13. *What is Power?
• *Power is the rate at which work
Work (joules)
is done.
Power (watts) P=W
t Time (sec)

14. Power:

16. Power Demo
• These two people did the same amount of work.
•The difference is Power: One person used more
Power and got the work done much faster
•A more powerful machine does the same amount
of work in less time

17. Review:
• Work = Force x distance

18. Your Turn…
• On your paper:
– Look through Chapter 5, Section 1
Pg 85-90
– Add more information from this
section into your notes.
(at least six items)

19. Practice:
• Skill Sheet 5-A
Example:
• How much work is done on a 10 N block
that is lifted 5 meters off the ground by a
pulley?
Work = F x d
W = 10N x 5 meters = 50 newton- meters OR 50
joules
Remember: newton-meters = joules

20. Work
• Work = Force x Distance
• Work is only done when
something is moved a distance in
the direction of the force.