Horsepower to watt

Watt-seconds = Joules.

Hi Codey,

i do agree with you. I did checked in all the books that I can find that should have electrical formula pertaining to Watt and Horsepower and I couldn't find any formula that could help me solve this problem.

Thanks.

Kollie

Hi Codemaster

1HP is 33,000ft.lbs./min or 550ft.lbs./sec, so time definitely does come into it. I believe Mr Watt the steam engine man harnessed a horse to pull a weight up a mineshaft in order to compare his engines to horses.

Tony

Hello Tonymech

I agree time comes into the definition of HP (and watt). I just meant time is irrelevant to the question asked - to find the watts of a motor that produces 100 horsepower in one minute.

Cheers........Codey

If you need the input power (Watts) for a 100 hp. output motor, you'll need to divide the output power by the efficiency of the motor. If the motor efficiency is 90%, then the input power is 100 hp * 746 W/hp /0.900 = 8290 Watts.

The same way. The horsepower of the engine is constant over time as is the wattage it can produce. So you have the theoretical potential for 74.6kw per sec / min / hour as long as the engine runs.

It is a matter of understanding the difference between energy and power.

Power is the rate at which energy is consumed. On the reverse, energy is power multiplied by time.

For example, if 700 watts is consumed continuously for one and a half hours, the energy consumed is 700 x 1.5 watt hours. ie. 1050 watt hours ( or simply 1.05 kilowatt hours ).

Rajan

You are compressing an hour and a half's consumption into one hour. Wrong. .7 kilowatt hours.

Guest nº8, sorry but you are wrong. the guest on post nº 7 is correct

chas

Hope this helps....HP = { (distance/time)*weight (lbs) } /550

Tq = (hp*5250) / RPM

Horsepower is already expressed in time. 1 horsepower is the power to lift 550 lbs in one second.

The manufacturer determines it, and states it on the rating plate to save anyone else the bother.

Lots of people talking round this, and, most getting it roughly right: but the fact that guest #8 still refuses to understand means it's still not quite clear, so I'll have a go.

Horsepower and Watts are both rates of work (whether input or output), so your original conversion (746 watts is equal to 1 horsepower) is correct.

If something works at 10 Watts then of course it can do 1 Watt hour of work in 6 minutes.

We don't normally use specific units for speed (knots and Mach are exceptions: I know), but say we define:

one bicycle = 10 miles/hour and

one car = 10 bicycles

Then that relationship would hold whether we looked at it for a minute or a day.

This is kinda like comparing the apple in my pocket to my hammer. How many apples are in a hammer?

watts and horsepower are POWER... thus 100 horsepower = 74,600 watts

Watts or horsepower over time is ENERGY. Someone defined joule as 1 watt second.

Thus the amount of ENERGY delivered by the motor in one minute would be

74,600 x 60 = 4,476,000 JOULES.

The meter on my house (from the power company) measures the ENERGY I use in Kilowatt hours. It doesn't care if I use a Kilowatt of power in one hour, or 60 Kilowatts of power in one minute. The ENERGY (and the bill) come out the same.

<...60 Kilowatts ...house...>

Provided the supply cable can support that kind of a load!

The one minute constraint is not on the motor for it to produce 100 hp.

The one minute constraint is on you... the time in which you should ... find the watts... i.e. answer the question.

You have clearly stated that the motor produces 100 HP in one minute .So it is a conversion of HP to watts or KW which 75 KW in one minute