Jon Gleghorn, age 14, of Bonita, Calif., for his question:

WHAT IS HORSEPOWER?

If an engine can lift a 550 pound weight to a height of two feet in one second, engineers say that the engine is lifting at a rate of 1,100 foot pounds per second. This is determined by multiplying 550 by two, and then dividing it by one. The engine would be delivering two horsepower.

A horsepower is a unit of measure used to express the power or rate of doing work. It is used to rate engines and other power producing plants.

A Scottish engineer by the name of James Watt is the first man to have used the horsepower term. In coming up with the word, he was making a comparison of the power in one of his steam engines to a number of horses.

Today the term has a broader meaning. It is used for rating the power of autos, jet engines, electric motors and even atomic reactors.

One horsepower is defined as 550 foot pounds of work per second. That figures out to 33,000 foot pounds of work per minute. One foot pound is the work needed to lift one pound one foot.

The metric unit of power is called a watt. You will have to have 745.7 watts of power to equal one horsepower.

Here is another horsepower example: If a man weighing 150 pounds climbs to a height of 88 feet, he has done 13,200 foot pounds of work. This is figured by multiplying the weight of the man (150) with the 88 feet he has climbed. If the man makes the climb in 60 seconds (one minute), he is working at the rate of four tenths of a horsepower. Here's the way it is figured: 13,200 divided by 60 equals 220. Then 220 divided by 550 gives you four tenths.

A number of different ways are used to measure the power of an engine. There is indicated power, brake power and S.A.E. horsepower.

Indicated power is a measurement of the power produced inside the cylinders of an engine. Brake horsepower, sometimes called effective horsepower, is the amount of power available at an engine's shaft. S.A.E. horsepower is a calculated rating approved by the Society of Automotive Engineers.

S.A.E. horsepower rating is computed by squaring the diameter of the cylinders, multiplying this value by the number of cylinders and then dividing by 2.5.

S.A.E. horsepower ratings are usually lower than both indicated and brake horsepower, while indicated horsepower is greater than brake horsepower.