work and power
TRANSCRIPT
![Page 1: Work and power](https://reader031.vdocuments.site/reader031/viewer/2022032100/55ccf3aabb61eb013e8b4604/html5/thumbnails/1.jpg)
WORK AND POWER
![Page 2: Work and power](https://reader031.vdocuments.site/reader031/viewer/2022032100/55ccf3aabb61eb013e8b4604/html5/thumbnails/2.jpg)
WHAT IS WORK?
When you do real work, you get tired. If you are smart, however, just exerting forces, shouldn’t get you tired.
![Page 3: Work and power](https://reader031.vdocuments.site/reader031/viewer/2022032100/55ccf3aabb61eb013e8b4604/html5/thumbnails/3.jpg)
Does holding a rubber band stretched get you tired?
![Page 4: Work and power](https://reader031.vdocuments.site/reader031/viewer/2022032100/55ccf3aabb61eb013e8b4604/html5/thumbnails/4.jpg)
What if you used a stick or a pencil to hold the rubber band stretched?
![Page 5: Work and power](https://reader031.vdocuments.site/reader031/viewer/2022032100/55ccf3aabb61eb013e8b4604/html5/thumbnails/5.jpg)
Do you think you are doing work when you hold a rubber band in a stretched position?
REMEMBER! You are just HOLDING it and you are
NOT MOVING either hand.
![Page 6: Work and power](https://reader031.vdocuments.site/reader031/viewer/2022032100/55ccf3aabb61eb013e8b4604/html5/thumbnails/6.jpg)
WORK! WORK! WORK!
![Page 7: Work and power](https://reader031.vdocuments.site/reader031/viewer/2022032100/55ccf3aabb61eb013e8b4604/html5/thumbnails/7.jpg)
Formula:
WORK = Force x Displacemente.g.
5 m
W = F x d = (10 N)(5 m) = 50 N.m or 50 J
10 N
![Page 8: Work and power](https://reader031.vdocuments.site/reader031/viewer/2022032100/55ccf3aabb61eb013e8b4604/html5/thumbnails/8.jpg)
Is he doing work?
![Page 9: Work and power](https://reader031.vdocuments.site/reader031/viewer/2022032100/55ccf3aabb61eb013e8b4604/html5/thumbnails/9.jpg)
Work? Or NOT Work?
![Page 10: Work and power](https://reader031.vdocuments.site/reader031/viewer/2022032100/55ccf3aabb61eb013e8b4604/html5/thumbnails/10.jpg)
Example problem:
Renatta Gass is out with her friends. Misfortune occurs and Renatta and her friends find themselves getting a workout. They apply a cumulative force of 1080 N to push the car 218 m to the nearest fuel station. Determine the work done on the car.
![Page 11: Work and power](https://reader031.vdocuments.site/reader031/viewer/2022032100/55ccf3aabb61eb013e8b4604/html5/thumbnails/11.jpg)
POWER
Power is the rate of doing work.
Power is work per time.
![Page 12: Work and power](https://reader031.vdocuments.site/reader031/viewer/2022032100/55ccf3aabb61eb013e8b4604/html5/thumbnails/12.jpg)
Formula:
![Page 13: Work and power](https://reader031.vdocuments.site/reader031/viewer/2022032100/55ccf3aabb61eb013e8b4604/html5/thumbnails/13.jpg)
Unit of Power
![Page 14: Work and power](https://reader031.vdocuments.site/reader031/viewer/2022032100/55ccf3aabb61eb013e8b4604/html5/thumbnails/14.jpg)
Power
The metric unit of power is the Watt
![Page 15: Work and power](https://reader031.vdocuments.site/reader031/viewer/2022032100/55ccf3aabb61eb013e8b4604/html5/thumbnails/15.jpg)
Example:
Ana weighs 50N and Lara weighs 35N. Mark carries each of them at 30 seconds and 20 seconds respectively. How much power does Mark apply to both of them if he carries each of them from a distance of 12 m?
Given: Ana’s weight: 50N Lara’s weight: 35N D: 12m
![Page 16: Work and power](https://reader031.vdocuments.site/reader031/viewer/2022032100/55ccf3aabb61eb013e8b4604/html5/thumbnails/16.jpg)
Solution:
Power = W/t Power = (F.d)/t Ana:
P = (50N x 12m)/30 s
= 600Nm/30s
= 20 Nm/s or 20 J/s
= 20 Watts
![Page 17: Work and power](https://reader031.vdocuments.site/reader031/viewer/2022032100/55ccf3aabb61eb013e8b4604/html5/thumbnails/17.jpg)
Other examples…
Interactive solving