View Full Version : Physics type question that has had me pondering!

8th Oct 2008, 15:09
On another off topic note i was pondering with my Dad (He's not sure of the answer!) but I have a 2kW Electric fan heater in my room and a conversion tool on my computer. When i convert 2kW into Horsepower the result is 2.682... hp. I was just wondering as to how a small electric motor used to turn a small fan is capable of providing the energy/momentum etc of over 2hp? That more like something you would find a small basic lawnmower engine to produce!?

Maybe the conversion tools I use are not ment for this sort of context or kW Vs. HP? Or does it mean over the course of a kilowatt HOUR that the motor will produce over 2hp??:confused:

Lewis :)

8th Oct 2008, 15:17
The 2 kw as depicted on a heater usually means the power consumed by the heating element itself rather than the fan motor. in this case 2 kw is determined by how many Amperes of current are drawn by the heating element..the formula is Volts x Amps = Watts so for example a 240v 2kw heater will draw just over 8 amps of current.

Would be rather cool to have a 2.6 horsepower heater tho :}

8th Oct 2008, 15:18

I'm sure your calculator is quite correct.

What you are overlooking is that the same two horses that are turning your fan are also warming your room. In fact they are working far harder to produce the warmth than to blow that warmth around your ears.

Gottit ???


8th Oct 2008, 15:24
Lew747, the answer is simple.

You're talking about a 2kW electric fan heater.
The fan itself will only be using something like 50W to 100W (just checked on a typical big indoor fan, which said 40W).

The rest is the heat from the heating element !


8th Oct 2008, 15:32
Horse Power (or HP) is just that, ie power, or the potential to do work.
Work can be done slowly or quickly (ie you can raise a weight or push a load) over a long time or 'in an instant' (well, not quite). You need more power to do work faster.
The unit of power (in certain units) is the watt (or Watt, named after James Watt, a Scottish engineer who developed the steam engine). A kiloWatt is a thousand Watts. If a kiloWatt (or a kW) is applied for one hour, an amount of work (a kiloWatt-hour) is done.
Of course there are conversion factors between HP and Watts as they are both units of power. You can imagine an electric motor rated in kiloWatts equating to a motor rated in HP.

8th Oct 2008, 15:42
Thanks for all your help! I can fully understand that now! I just mis-judged thinking that 2kw is what the actual motor was outputting. Completely forgetting about the heating element!

I'm silly :}

8th Oct 2008, 15:51
hahahaha :D I like that lol!

I've taken out this physics course from Oxford Open Learning and I think PPRuNe is the best place to get all the answers i need! :):ok:

green granite
8th Oct 2008, 15:52
I had a 2 oars power boat onceThat sounds fairly 'armless Prophead

8th Oct 2008, 16:59
Oh, thank God.... I thought this was another conveyor belt question. :ooh:

8th Oct 2008, 17:05
I've taken out this physics course from Oxford Open Learning Are they the ones that issue you with an ATPL on completion of your course?

8th Oct 2008, 17:10
Would be rather cool to have a 2.6 horsepower heater tho

cool ?


Loose rivets
8th Oct 2008, 17:20
I had a 2 oars power boat oncehttp://static.pprune.org/images/smilies/badteeth.gif
Sounds like a load of Rollocks to me.:E

Did you know that letting your oar slip out of a rollock and falling backwards into yer boat, was called catching a crab?

Fish pun alert.

8th Oct 2008, 17:30
The oar needn't necessarily come out of the rowlock, in fact (in proper rowing - the sort where eight oarspeople each have an oar each) it's more usual for the oar to remain in the rowlock and the handle passes over the rower and ends up behind them (and the blade buried deep in the water).
Bit of a buggah to retrieve in the middle of a race too . . .

catching [email protected] (http://everything2.com/index.pl?node_id=1014179)

8th Oct 2008, 17:31
Oh, for cod's hake, rivets ... there's a plaice for these things, you know.

8th Oct 2008, 17:33
Oh, thank God.... I thought this was another conveyor belt question.

Or is not!!!
The Fan!!!!
On a conveyor belt. ?


And where's that nurse with my pills. Mumble, mumble.

cockney steve
8th Oct 2008, 18:10
does a 2-whores brothel count?

(you could put them on a conveyor -belt going through multiple client-booths :}

8th Oct 2008, 19:17
That sounds fairly 'armless

For a long time we doctors thought the same about thalidomide . . . . . . . :ugh:

Captain Stable
8th Oct 2008, 19:22
I had a 2 oars power boat onceAre we going to have a row about this?

8th Oct 2008, 19:54


8th Oct 2008, 20:09
What about the cox?

Takan Inchovit
8th Oct 2008, 20:17
Oh hull, here we go again.

8th Oct 2008, 21:22
She was only the Rowing Masters Daughter ....but she stroked the cox of the crew.:O

cockney steve
8th Oct 2008, 22:44
she was only the captain's daughter, but she knew how to mate.

Loose rivets
9th Oct 2008, 17:28
I can row a boat...canoe ?

(better asked verbally I suppose)

G-CTPN, That brings back some memories. Yes, I see what you mean. The ore seems to get sucked down sometimes and twists to some obscure angle that is designed to get it entwangled with another. I can imagine the looks on the other crew's faces.:*

9th Oct 2008, 18:54
twists to some obscure angel

A devil in disguise?

9th Oct 2008, 18:58
Rowlocks to you too! :*

10th Oct 2008, 03:55
Time came last year to sell off an older-model "airport car" that one used to park at a remote aerodrome so as to have some trusty transport when arriving there at odd hours. Main thing one wants in such a car is that it will start every time, go where necessary, and not be at all attractive to joy-ride thieves. So it was old, never washed or polished, and really out of style, but still comfortable and, in that isolated place, could occasionally serve as hotel as well.

Looked it up on the net when trying to think how to sell it. Only feature with any market appeal was the rather large engine - 8 cyls and 460 cubic inches displacement. What a shock it was to see that rated for power, in Wikipedia, at 313KW! Not so surprising it worked through fuel like a sieve.

Loose rivets
10th Oct 2008, 04:21
Huh! One had a 57 Olds 88 parked at Ipswich for the purpose of getting some serious wooing done.

At last! She agreed to come on a night stop, we'd drive to the old homestead at Walton. We landed the DC3 and while I was putting it to bed (The plane!) there was a screeeeeeeeeeetching of tires outsde. Her bloke had driven the 70 miles in nearly the time it had taken us to fly there. How history might have been altered that night if he'd been rather less determined. :suspect:

10th Oct 2008, 05:57
Her bloke had driven the 70 miles in nearly the time it had taken us to fly there.

Likely had you figured and was "motivated" to get there before the opportunity took solid hold.

10th Oct 2008, 07:00
I think PPRuNe is the best place to get all the answers i need!

You will probably live to regret making that assertion.