Re: [DMCForum] ATTN: Jim Strickland -- "300 HP" Does *NOT* Mean "300Horses Coupled Together"

[Martin Gutkowski <webmaster@xxxxxxxxxxxxxx>]

content22207 wrote:

>You've got the equation a bit backwards: HP = Torque x RPM /5252. I'm
>not making "$hit" up -- that's how HP is calculated. 
>
Only if you measure torque in ft-lbs. The correct statement is that HP 
is a product of torque and speed. The fact that you also multiply by an 
arbitary constant makes no difference as it's unitless. Which brings me 
onto my next bit...

>HP is basically a measure of TIME, 
>
Utter utter utter bollocks. HP is a unit of power and is (from memory) 
equal to 768W. A watt is 1 joule of energy transferred in one second. 
Again from memory, it's the energy required (in a 100% efficient system) 
to lift a mass of 1kg to a height of 1m at sea level (gravity = 
9.81m/s^2 meaning a force of 9.81Newtons is acting in the opposite 
direction). If you do it in 1 second, you've made your 1 watt. Lift it 
in half a second, and it'll take 2W of power to do it. You can do it 
over 2 seconds and the power required is half a watt. Get where I'm 
going with this? Power is directly proportional to speed and in this 
case, we're keeping the force Torque is rotational force, measured in 
terms of newton metres - ie 1Nm is the rotation induced by a metre long 
stick with a 1N weight on the end.

I dont know what age you guys did this basic physics at school, but I 
did it at 14-16.

>I *HAVE*
>seen vehicles with low torque engines struggle to reach the top of a
>long steep grade with NOTHING coupled to their rear.
>
OK, and what did your driving instructor tell you to do in dire 
circumstances like this? Turn around and do it in Reverse as it's the 
HIGHEST GEAR.

Martin

>  
>

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