[Lab] Fwd: energy requirement of toast
darcy at siteware.com
Wed Jul 27 10:09:35 EDT 2011
I'm just about to publish this. I think I made an error somewhere since I
expected 1/4 hp to be more than climbing 4-5 floors per minute for an adult
Steve over at <a href="http://canadianenergyissues.ca"
target="_blank">Canadian Energy Issues</a> brought this to my attention.
He's an environmentally conscious person that works in the entertainment
industry. He says he was making toast from his pedal bike.
<blockquote>Skip ahead to 00:24:45
Okay, I'm making toast now. I'ts just passing a minute as I type this
My toaster does not say what the wattage is. I will either measure it or
find a similar toaster on the Web and see what kind of power we're talking
Two minutes and toasting.
I just found a nice <a href="
of appliance consumption</a>.
This is all very confusing because I'm listening to the podcast at the same
Okay, the appliance consumption table suggests 800-1500 Watts. I was
guessing about 1000 Watts so this all makes sense.
For those of you that are less familiar with energy, a horsepower is about
746 Watts. Humans are typically known for producing about 1/10th of a
horsepower. Okay, I met a guy at green drinks once who said he can put out
about 1/2 horsepower on his bicycle for a period of time. He said he had a
measuring device on his bike but I doubt it was calibrated and that he knew
a lot about measurement.
So if the toaster is 1000 Watts, we now under stand how hard the peddling
must be done.
My toast was done in 3m 15 seconds. So lets use just 3m just for roundness
in this estimate.
Ed says he can pedal for 15m to make toast. My 3m toast goes into 15m 5
times. So he can pedal for five times as long as needed. So he can pedal at
1/5 the actual power required for toast of he can generate and store the
energy efficiently and then let it all happen in three minutes. So the
duration of the toast making would be 18m. 15m Of mad pedaling and then 3m
of toasting with the stored energy.
Hmmm, lets see, 1000 Watts divided by 5 is 200 Watts. That's just over 1/4
Assuming you have efficient generation and storage and reuse of the energy,
it takes 15m of 1/4 horsepower pedaling to make toast.
Let's put that in stair climbing terms so we can "Feel the Power".
A horsepower is 550 foot-pounds/second according to my distant memory. :)
That means it's enough power to lift 550 pounds one foot in one second. Or
one pound to a height of 550 feet in one second.
He's doing 1/4 of that.
So we're talking 138 foot pounds per second.
Fifteen minutes of pedaling is 900 seconds which means he is doing 124,200
foot pounds of work. Wow, I hadn't realized it takes 120 thousand foot
pounds of work to make toast.
I just googled Ed to see a picture of him to guess how much he weighs. I'm
very scientific. :)
Um, okay he looks like a thin/fit guy so let's give him 175lb. I understand
he'd tall so perhaps we should kick another 15lb? Perhaps 190lb?
To "Feel the Power" we need to divide 190lb into the 124,200 foot pounds and
see how high to climb stairs in 15m. That comes to 654 feet.
How many floors high is this? Well at 10 feet per floor that's 65 floors in
That's only 4-5 floors per minute.
So that's pretty doable as long as he has a high efficiency system.
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