1. Work, Power, and Machines

2. Work
How the world works….
The way of the Work

3. Work …. Work …. Can you work overtime
Dude! I need a raise

4. What is work?
In science, the word work has a different meaning than you may be familiar with.

5. Work Work = force x distance W = Fd
The product of the force applied to an object and the distance through which that force is applied.
Work = force x distance
W = Fd

6. Work
Work is measured in:
Nm
Joules (J)

7. The unit for work is the Joule
To measure work, you must know the force (N) and the distance (m)
The unit for work is the Joule
We work to make money to buy “joules”.

8. *Work is only done when the force is in the same direction as the object moving*

9. Energy
can produce a
Force
which can move something to do
Work

10. Work or Not?

11. Is work being done or not?
Mowing the lawn
Weight-lifting
Moving furniture up a flight of stairs
Pushing against a locked door
Swinging a golf club
YES NO

12. Work Example
A crane uses an average force of 5200 N to lift a girder 25 m. How much work does the crane do?

13. Work Example Work = Fd Work = (5200 N)(25m) Work = 130000 N  m
= J

14. History of Work
Before engines and motors were invented, people had to do things like lifting or pushing heavy loads by hand. Using an animal could help, but what they really needed were some clever ways to either make work easier or faster.

16. Work= Force x Distance W F D
Work- Joule (J)
Force-Newton (N)
Distance-Meter (m)

17. Work- Force- Distance- W= Fd 15N x 2m = ? 15N 2m 15N 2m 30J
If you lift a bag that weighs 15 N a distance of 2 m, how much work have you done?
Work-
Force-
Distance-
W= Fd 15N x 2m = ?
15N 2m
15N 2m
30J

18. 2. A 950 N skydiver jumps from a plane that is 3000 m high
 2. A 950 N skydiver jumps from a plane that is 3000 m high. What is the total work performed on the skydiver?
Work-
Force-
Distance- ?
950N
3000m
950N
3000m
2,850,000J

19.  3. A bulldozer performs 80,000 J of work on a load of dirt that is moved 16 m. What is the force of the dirt?
Work-
Force-
Distance-
F=W/d
80,000J
80,000J ?
16m
16m
5000N

20. 4. How much work is done by a person who uses a force of 27
 4. How much work is done by a person who uses a force of 27.5N to move a shopping cart 12.3m?
Work-
Force-
Distance- ?
27.5N
12.3m
27.5N
12.3m
338.25J Or
338.3J

21. 5. A force of 10,000 N is used to push on a stationary wall
 5. A force of 10,000 N is used to push on a stationary wall. How much work is done?
Work-
Force-
Distance-
W= Fd ?
10,000N 0m
10,000N 0m 0J

22.  Do Now
1. How much work does a tiger do while moving a ball, in a circus, 5 meters with a pulling force of 11N?
Work-
Force-
Distance- ?
55J
11N 5m
11N 5m

23.  DO NOW
2. Joe balances a stationary coin on the tip of his finger 20cm from the top of the table. Gravity is pulling with a force of 5.67g. How much work is Joe doing?
Work-
Force-
Distance- ? 0J
(mass 5.67g)
.05N 0m 0m