Test Pulleys, Gears, and Levers Questions and Answers Flashcards

A pulley system uses one fixed pulley and one movable pulley. How many rope segments support the movable block?

Answer: 2

A single movable pulley has 2 rope segments supporting the load block, giving a mechanical advantage of 2.

Gear A has 20 teeth and drives Gear B with 20 teeth, which in turn drives Gear C with 40 teeth. What is the overall speed ratio from Gear A to Gear C?

Answer: 1:2

Stage 1 (A to B): 20 divided by 20 equals 1:1 (same speed). Stage 2 (B to C): 20 divided by 40 means C runs at half of B speed. Overall: Gear C turns at half the speed of Gear A, giving a 1:2 ratio.

A Class 3 lever always has the effort applied between the fulcrum and the load. What is always true of a Class 3 lever?

Answer: MA is always less than 1, requiring more effort force than the load

Class 3 levers always have the effort arm shorter than the load arm, so MA is always less than 1 and more effort is required than the load weight.

A worm gear system has a worm with 1 thread and a worm wheel with 40 teeth. The worm turns at 400 RPM. At what RPM does the worm wheel turn?

Answer: 10 RPM

Worm gear ratio equals worm wheel teeth divided by worm threads: 40 divided by 1 equals 40:1. Worm wheel RPM equals 400 divided by 40 equals 10 RPM.

A firefighter applies 80 lbs of force to a lever handle. The fulcrum is 6 inches from the load end and the handle is 24 inches long total. What is the mechanical advantage?

Answer: 3

Effort arm equals 24 minus 6 equals 18 inches; load arm equals 6 inches; MA equals 18 divided by 6 equals 3.

Two intermeshed gears rotate in which direction relative to each other?

Answer: Opposite directions

Two intermeshed gears always rotate in opposite directions — when one turns clockwise the other turns counterclockwise.