Unit 6 Work and Machines

Power

Definition: Amount of work done in a certain amount of time; rate at which work is done.

Explanation/Notes: Power is the amout of work done in a certain amount of time and the formulas are power equals work divided by time and power equals energy divided by time. Power is measured in Watts.


Formula: P=W/T & P=E/T

Units: Power is measured in watts (W).

Sample Problem:

Calculate the Power if:

It takes 3 seconds to move a 100 Newton object 25 meters.

W=F*D
P=W/T

D= 25 meters
F= 100 Newtons
T= 3 Seconds

P= (25m)(100N)/3 sec
P= 833.33 Watts

Everyday Example:

If you rockclimb at a slow rate, your power will be slow, but if you rockclimb at a faster rate then your power will increase.

Image:



This picture shows a woman walking and running up the stairs. The work is the same, but more power is needed to do it faster.



Video: Sample Problems