We are in the market for a new car. My analytical husband designed a spread sheet. The factors included such items as horsepower and torque. They seemed to be dependent, but not precisely.

The definition of horsepower was defined by James Watt, the steam engine inventor. He was observing a pony lifting 220 pounds of coal a height of 100 feet out of a mine in one minute. Though ponies were used in mines due to their diminutive size, Mr. Watt assumed a full-size horse could lift 50% more, or 330 lbs.

Funny, that the international standard (metric system) unit of power used today is the watt. One horsepower is about 7 to 10 light bulbs, or 746 watts.

Torque is rotational energy, the amount of power required to rotate a load around an axis.

Though we are still using our United States customary unit system, we need to convert our units slightly. Horsepower is converted to ft-lbs/min. Revolutions are converted to radians, or the distance around a unit circle.

So, 100 horsepower at 2000 rpm will provide about 260 torque. Since a car functions on rotational energy, the ability to move her tires, torque is the measurement of actual results. How fast can you accelerate? For some cars, the engine will require an increase of RPMs in order to achieve the desired power.

This is all a very interesting exercise. Nevertheless, in the minivan category, I am really only concerned with how many kids, musical instruments, sports equipment and groceries I can fit in one car.