Non Sequitur by Wiley Miller for November 15, 2010

1 H.P. = 745.7 Watt Hours.

Horse Power is work over a period of time. There is also an equation for converting Lbs/Ft. into Watts or Lbs. of thrust to Horsepower at altitude for jets.

Dammit Wiley, I just Googled that factoid ‘cause you piqued my curiousity. Shoulda known you’d make sure the numbers were correct.

Dear Ed: one man can’t beat Google. They’re too big for you. Get a hobby–reading books to the hospitalized, selling homemade lemonade, doing legerdemain–whatever.

Ed’s an engine search.

Use of Horsepower was originally attributed to James Watt as a readily understood contemporary measurement of work in the late 1700s.

@JoeMinotaur - Ed (or Wiley) is right. Both horsepower and watts are units of power, not work. Watt-hours are units of work. Power is work per time. (I’m amazed nobody else pointed this out in six hours. And I think Fairportfan2 even agreed with you.)

@ClarkKent - What you say is true – and totally irrelevant. It doesn’t change one iota the fact that 745.7 watts equals one horsepower. Both are units of power, plain and simple. You are probably assuming (incorrectly) that watts are only used to measure power in and horsepower to measure power out. That’s a common advertising practice, but not basic physics or engineering.

Thanks to you fellow commenters: you saved me looking for it!

A horsepower is ~746 Watts, not Watt-hours. Watt hours are a measure of energy. Watts are already a measure of energy transfer over time.

That would be why the unit is called a Watt, named after James Watt, the guy who came up with the calculated number of Watts to a horsepower.

Some references:

Princeton: http://www.google.com/search?hl=en&client=safari&rls=en&defl=en&q=define:horsepower&sa=X&ei=ujfhTOiFK4K8lQe20sDzAw&ved=0CBMQkAE

Wikipedia: http://en.wikipedia.org/wiki/Horsepower

And a cool car site that goes on to talk about brake horsepower: http://www.web-cars.com/math/horsepower.html

Now if we could only define a ‘standard’ horse to include Lucy!

Easy way to think about it in everyday terms - a lightbulb burning at a rate of 100 watts,, is the same kind of measure as an engine running at a rate of 250 HP,, as dtut says - work/time… I’m sure Wiley vets his info pretty thoroughly.

Clark Kent, Is that why women start getting hot flashes when they get older?

I retired so I didn’t have to think about this stuff anymore

and I still have my slide-rule

thanks Wiley

;)

@Somebodyshort’s post - interesting fact brought to mind that ties together a lot of the comments here. Many industrial reciprocating internal combustion engines are rated by “Brake Specific Fuel Consumption” - that is fuel consumption per Horsepower Hour,, Typically about 8000 BTU / HP-hr - since fuel values are usually measured in BTU/lb or BTU/scf. If engines were 100% efficient, that number would be 2545 (see SS post),,, so an easy way to calculate engine efficiency is to divide 2545 by the BSFC. In the typcial case – about 32%. The rest goes to heat, friction, incomplete combustion, etc…

WHOA, Jack… you just descended into the NERD zone… sorry…

Hey check out this website I found through Woot.com: http://www.weirdconverter.com/

It does all sorts of bizarre conversions.

Does anyone really care? OK-you are all a lot smarter than I am so I have nothing to add.

Doesn’t that Blogger from a few months ago live in the basement of this tenement?

One horsepower = a cowboy with his face in the dirt.

@jackmatt - Cool factoid. Like it. Don’t worry about the nerd zone; I lived there a long time myself. Retired now, but can switch the nerd on at will. Which brings me to:

@somebodyshort - The three laws of thermodynamics are:

(1) Energy can neither be created nor destroyed. (2) All thermodynamic processes are less than 100% efficient. (That’s entropy, as you correctly identified it.) (3) All real physical processes follow the laws of thermodynamics.

One of my classmates at MIT (told ya I was a nerd) expressed these laws as:

(1) You can’t win. (2) You must lose. (3) You have to play the game.

How many watts does it take to power a horse?

@dtut, or reformulation was:

You can’t win. You can’t even break even. You can’t get out of the game.

itś a cartoon. laff. or leave. get real.

Wow, the things I never learned nor have to remember… Thanks for reminding me…

“Genius is pain.” - John Lennon (MY BRAIN HURTS!) lol

So, bmonk, you’re saying the IRS obeys the laws of thermodynamics?

me thinks john hodgeman may have a litigious claim… Oh and useless information? Why do I know the lyrics to Gilligan’s Island? FIIK… Nature of the beast…

@bmonk - I like your reformulation.

Just remember that a person can generate about 2 HP… a horse about 10.