Horsepower required to lift a load

Aviation Mechanic General (AMG) practice question 1 of 20 on Physics for Aviation. ACS element AM.I.J.K1 · difficulty: applied. Want to answer it in a timed quiz? Use the Aviation Mechanic General (AMG) practice mode.

Question bank updated 2026-09-22

QUESTIONA hoist raises a 3,300-lb component a vertical distance of 10 ft in 2 minutes. How much horsepower is the hoist developing?

A1.0 hp
B16.5 hp
C0.5 hp

Show the answer and explanation

Correct answer: C. 0.5 hp

A — incorrect This results from ignoring the 2-minute time period. 33,000 ft-lb of work spread over 2 minutes is only 16,500 ft-lb/min, which is half a horsepower.
B — incorrect 16,500 ft-lb/min must be divided by 33,000 ft-lb/min, not by 1,000, to convert to horsepower.
C — correct Power = force × distance ÷ time = 3,300 lb × 10 ft ÷ 2 min = 16,500 ft-lb/min. Dividing by 33,000 ft-lb/min per horsepower gives 0.5 hp.

BACKGROUND

Work is force acting through a distance and is measured in foot-pounds. Power adds the element of time: Power = Force × distance ÷ time, with units such as foot-pounds per minute or per second. One horsepower (hp) was defined from the work an average horse could do and equals 550 ft-lb/s, 33,000 ft-lb/min, 375 mile-pounds per hour, or 746 watts. To convert a power figure to horsepower, divide by the conversion factor that matches the units of distance and time used.

STUDY TIP

Memorize 33,000 ft-lb/min and 550 ft-lb/s, and always check whether the problem gives time in minutes or seconds before picking the divisor.

KEY POINTS

Power = Force × distance ÷ time
1 hp = 550 ft-lb/s = 33,000 ft-lb/min
Divide the power figure by the matching conversion to get horsepower

SOURCES

FAA-H-8083-30B ch05 "Power"

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