AboutAbe Mantell Expertise Hello, I am a college professor of mathematics and regularly teach all levels from elementary mathematics through differential equations, and would be happy to assist anyone with such questions!
Experience Over 15 years teaching at the college level.
Organizations belong to NCTM, NYSMATYC, AMATYC, MAA, NYSUT, AFT.
Education/Credentials B.S. in Mathematics from Rensselaer Polytechnic Institute
M.S. (and A.B.D.) in Applied Mathematics from SUNY @ Stony Brook
An electric light bulb, for example marked “ 60 watts“, indicates that the bulb uses 60 watt-hours of electricity in one hour.
I can understand that the bulb uses 60 watts of electricity per hour, but I am confused by the 60 watt-hours per hour. How are watt-hours determined to get watt-hours per hour?
I thank you for your reply.
ANSWER: Hello Kenneth,
Well, if the bulb consumes 60 watt-hrs of power in one hour, then the
rate of power consumption is 60 watt-hrs per hour. If this bulb were
on for 3 hours, for example, then the total power consumption would be
60 watt-hrs/hr * 3 hrs = 180 watt-hrs.
Does that help?
Abe
---------- FOLLOW-UP ----------
QUESTION: Hello Abe:
I want to thank you for your reply, but I still do not quite understand. It is correct to have miles per hours.
But would anyone write or say mile-hours per hour?
I do not understand the watt-hours. I appears that watts have been multiplied by hours to get watt-hours.
I thank you once again for your reply.
Answer Miles per hour per hour would represent a rate of acceleration.
For example, 10 miles/hr per hr would mean every hr the speed of
an object is increasing by 10 miles/hr. See?
Anyhow, regarding the original question...
Think of it work...you've heard the expression "man-hours"...yes?
If a job will take 100 man-hours, it would take 1 man 100 hrs, or
2 men 50 hrs each, or 4 men 25 hrs each, etc. So 100 watt-hours is
like having a 100 watt bulb on for 1 hour, or a 50 watt bulb on
for 2 hrs, or a 25 watt bulb on for 4 hrs, etc.
