SOLUTION

Horsepower (hp) is a calculation of the rate at which work is performed; it measures an engine’s power output as a function of both torque and engine speed. James Watt (1736-1819), an engineer who helped make significant improvements to the steam engine, developed the formula to determine an engine’s hp. Watt wanted to compare the power of a steam engine to the number of horses required to perform the same amount of work. He based his calculation on observations of horses.

The horsepower range of other steam locomotives varies between 1,000 horsepower, to 2,000 horsepower. The Union Pacific “Big Boy” steam locomotive was rated at 6,290 HP.