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19 questions from the mechanical aptitude practice test.
10 questions, graded as you go, with the reason for every answer. No sign-up.
A rope is tied to the ceiling, passes down under a pulley hooked to a 120 lb load and back up to a worker's hand. Ignoring friction and the pulley's weight, what upward pull holds the load?
Answer in lb.
60 lb
Two rope segments support the movable pulley, so pull = 120 lb ÷ 2 = 60 lb.
Reference: Simple machines: pulleys and block and tackle
A block and tackle has 4 rope segments supporting the lower block. Ignoring friction, what pull lifts a 600 lb engine?
Answer in lb.
150 lb
Ideal MA = number of supporting segments = 4. Pull = 600 lb ÷ 4 = 150 lb.
Reference: Simple machines: pulleys and block and tackle
A tackle with 4 rope segments supporting the load raises it 3 ft. How much rope must the worker pull through?
Answer in ft.
12 ft
Each of the 4 supporting segments must shorten by 3 ft, so rope pulled = 4 × 3 ft = 12 ft.
Reference: Simple machines: pulleys and block and tackle