Re: POWER vs TORQUE
Torque is measuring twisting force. You have a torque wrench you set it to 10nm, it will apply 10nm of torque. 1 nm, is one newton of force at 1 metre of leverage.
Power is a little more complicated. Power is kind of a description of its ability to do work.
In the early days, power was use to describe the ability of say a horse to carry a bag of coal up a shaft. Its basically torque measurement over time. Watt came up with this "horse power" measurement so he could sell his machines. It emphasised that while horses and humans could lift a lot of things, on average, they were pretty slow, machines would perform this work extremely steadily with no rest, and thus win out.
I can have a little 2 stroke engine that makes about 5 Hp, but lets say, 50nm of torque. 50Nm isn't a great deal of torque, I can make about that much torque with a crankshaft style screw driver with my bare hands. But a engine can do it about 10,000 rpm, which I certainly cannot do. You can gear that little 2 stroke down so at the same RPM I make say my 75nm, it would be making thousands of Nm of torque. I will get pretty tired after 15 minutes, but the engine will keep going strong for hours or days given the fuel. Power takes that into concideration, the speed it makes its torque.
James watt actually overstated his estimation of the ability of a unit of "horsepower" so that there would not be any complaints that these new steam machines were not able to live up to the rated power. Its one of the reasons why the industrial revolution happend so quickly.
Also a car with 1 HP that weighs the same a large horse does not mean that it will be as quick as horse over 200 metres. Thats not where that measurement of power came from.
You can calculate the power of a engine if you know the torque and RPM of that torque, but your calculation is the power produced at that RPM.
So power and torque are heavily related. Torque is the turning force of the engine. Power is basically the torque at a certain RPM point.
A great number of people get confused by what is power and what is torque and how they are related.