Numbers

4-14 Concept of Power

Return to Home Page

Lesson List


Power is the measure of the time in which work can be done.  If two people, each weighing 100 pounds, begin to walk a mile, each will use power to complete the walk.  Walker 1 completes the walk in 30 minutes, while walker 2 completes the walk in 60 minutes.  Each walker is the same weight and walks the same distance.  They each have done 528,000 foot-pounds of work.  100 pounds X 5,280 (feet in a mile) equals 528,000 foot-pounds of work.  Power applies to work over time.

The power of an engine is rated in horsepower.  One horsepower is 55 pounds X a distance of 10 feet over one second of time.  Or 550 foot-pounds per second.

Walker 1 must have had more horsepower to complete the walk quicker than walker 2.  Lets use the formula to determine the horsepower of each walker.

Since each walker weighed 100 pounds and each walker traveled a distance of 5,280 feet, each walker did 528,000 foot-pounds of work (100 X 5,280 = 528,000).  But walker one did the work in half the time and most likely had more horsepower.  Let's solve the formula.

Walker 1:  528,000 foot-pounds divided by 1,800 seconds (30 minutes X 60 seconds) equals 293.33 foot-pounds per second.

Walker 2:  528,000 foot-pounds divided by 3,600 seconds (60 minutes X 60 seconds) equals 146.66 foot-pounds per second.

Neither walker had as much horsepower as a horse does during the walk.

Complete the questions below.

 

Power is the measure of in which work can be done.

Power applies to over .

Horsepower is the divided by .

One horsepower is foot-pounds per second.

If a 200 pound runner completed a mile race in 10 minutes, how much horsepower did the runner put out?
foot-pounds per second

If a 100 pound runner completed a mile race in 10 minutes, how much horsepower did the runner put out?
foot-pounds per second

 

 

Elementary & Middle School Lessons & Self-Correcting Tests for Children in all Subject Areas.
If you have found an error or would like to make comments on this lesson, please email us at:
MySchoolhouse.online@gmail.com

Copyright 1999-2020 by Educational Designers, LLC.  All rights reserved.
Lessons & Tests in Math, Reading, Spelling, Science, Language, and Social Studies.

"This site uses cookies from Google to deliver its services and analyze traffic. Your IP address and user-agent are shared with Google along with performance and security metrics to ensure quality of service, generate usage statistics, and to detect and address abuse."
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
WORK SPACE
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Power Equals Work Divided by Time