FCTC Test Pulleys, Gears, and Levers Questions and Answers Flashcards

A lever in equilibrium has a 50 lb load 4 feet from the fulcrum. How much effort is needed 10 feet from the fulcrum on the opposite side?

Answer: 20 lbs

Using the lever equation: effort × 10 = 50 × 4, so effort = 200 ÷ 10 = 20 lbs.

Which scenario correctly describes an idler gear in a gear train?

Answer: It reverses the direction of rotation without changing the gear ratio

An idler gear placed between two gears reverses the direction of the driven gear without affecting the overall gear ratio.

A snatch block is a type of pulley used in rigging. What makes it different from a standard pulley?

Answer: It can be opened to insert a rope without threading the end

A snatch block opens on the side so a rope can be inserted midway without needing access to the rope's end.

If a first-class lever's effort arm equals its resistance arm, what is the mechanical advantage?

Answer: 1

When effort arm = resistance arm, MA = effort arm ÷ resistance arm = 1, so no force multiplication occurs.

A worm gear set has a worm with 1 start and a worm wheel with 40 teeth. What is the gear reduction ratio?

Answer: 1:40

With a single-start worm, one full worm rotation advances the wheel by 1 tooth, so the ratio is 1:40.

Which class of lever always has a mechanical advantage less than 1?

Answer: Third-class

Third-class levers always have the effort between the fulcrum and load, making the effort arm shorter and MA always less than 1.

In a pulley system, what effect does friction in the pulley bearings have on the system?

Answer: It reduces actual mechanical advantage below the ideal value

Bearing friction requires extra effort force, reducing the actual mechanical advantage below the theoretical ideal.