Clinton Richardson, age 13, of Haysville, Kansas, for his question:

What does an engine of so much horsepower mean?

The modern automobile often has enough horsepower to exceed every speed limit law in the land. Its horsepower is the energy its engine can call on to perform the work of making the car run. The horsepower unit is a complex measurement of working strength and time. Its strength or energy quota is based on the foot pound, a unit of work needed to lift a pound weight one foot off the ground. It takes two foot pounds to lift one pound two feet and the same amount of foot poundage to lift two pounds a distance of one foot.

The horsepower unit is based on the energy in 550 foot pounds. However, it has an added factor, time. It must exert enough effort to lift 550 pounds a distance of one foot in one second. The horsepower of an engine is estimated on the amount of work it can do at a certain rate. A three horsepower engine can work as hard as about four strong horses. However, it may be designed to use its power to run a little generator and do all sorts of things no horse could ever do.