This presentation is the property of its rightful owner.
1 / 12

# Power PowerPoint PPT Presentation

Power. Work has to do with a force causing a displacement . It has nothing to do with the amount of time that this force takes to cause the displacement. Consider a rock climber… he may ascend a few meters very slowly.

Power

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

## Power

• Work has to do with a force causing a displacement.

• It has nothing to do with the amount of time that this force takes to cause the displacement.

• Consider a rock climber… he may ascend a few meters very slowly.

• A hiker can ascend the same height in far less time by taking the easier path.

• They do the same amount of work, but the hiker does it much quicker.

• The amount of work done over time is called power.

• The hiker has a better power

rating than the rock climber.

P = W/t

P- Power

W- Work

t- time

• W= Fd (when force and displacement vectors are in the same direction)

• P= W/t

• P= Fd/t

• d/t = v

So………

P =Fv

• Unit of measurement for power: the Watt (W).

• 1 Watt = 1 J/s = 1 kg m2/s3

• Named after James Watt (b. 1736), an engineer whose improvements to the steam engine were very important to the Industrial Revolution.

James Watt (Scottish)

• You often see power measure in horsepower

• 1 horsepower (hp) = 746 W

• The term was adopted in the late 18th century by James Watt to compare the output of steam engines with the power of draft horses

• Machines, people, animals, etc. all have power ratings.

• I.e., the amount of work over time. More work over less time means a higher power rating.

### Example

• A 70 kg jogger runs up a long flight of stairs in 4.0 s. The vertical height of the stairs is 4.5 m. Estimate the jogger’s power output in both watts and horsepower.