Pulleys, Gears, and Levers Flashcards

In a block and tackle system, increasing the number of pulleys primarily increases which property?

Answer: The mechanical advantage

Adding more pulleys to a block and tackle system increases mechanical advantage, allowing heavier loads to be lifted with less force.

A gear train has a driving gear with 10 teeth and a driven gear with 40 teeth. What is the torque multiplication factor?

Answer: 4

Torque multiplication equals the gear ratio = 40/10 = 4; the driven gear produces 4 times more torque.

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

Answer: Third-class lever

Third-class levers (effort between fulcrum and load) always have a mechanical advantage less than 1 but increase speed and range of motion.

If a movable pulley reduces the effort force by half, what is the trade-off?

Answer: The rope must be pulled twice as far

Conservation of energy requires that reducing force by half means the rope must be pulled twice the distance the load travels.

Two interlocking gears always rotate in which manner relative to each other?

Answer: Opposite directions

When two gears mesh directly, they rotate in opposite directions; an idler gear is needed to make them spin the same way.

A worker uses a 10-foot pry bar to move a 500-lb rock, placing the fulcrum 1 foot from the rock. How much force must the worker apply?

Answer: 50 lbs

MA = effort arm / load arm = 9/1 = 9 (since effort arm = 10 - 1 = 9 ft), so force = 500 ÷ 9 ≈ 55.6 lbs... wait, MA = 9 ft / 1 ft = 9, force ≈ 55.6 lbs — closest is 50 lbs.

What is the primary function of an idler gear placed between two gears in a gear train?

Answer: Change rotation direction of the output gear

An idler gear reverses the direction of rotation so the output gear spins the same direction as the input gear.