Pulleys, Gears, and Levers Flashcards

A pulley system requires a worker to pull 12 feet of rope to raise a load 3 feet. What is the mechanical advantage of the system?

Answer: 4

Mechanical advantage = rope pulled ÷ load distance = 12 ÷ 3 = 4.

A nutcracker is an example of which class of lever?

Answer: Second-class

A nutcracker is a second-class lever — the fulcrum is at the hinge end, effort is at the handles, and the nut (load) is in the middle.

In a gear train, which gear arrangement is used to convert rotational motion into linear (straight-line) motion?

Answer: Rack and pinion

A rack and pinion system converts the rotational motion of a circular gear (pinion) into the linear motion of a flat toothed bar (rack).

If friction is present in a pulley system, how does it affect the actual mechanical advantage compared to the theoretical value?

Answer: Actual MA is lower than theoretical

Friction reduces the actual mechanical advantage because some input force is lost overcoming friction, meaning more effort is needed than theory predicts.

A lever has a load of 300 lbs placed 2 feet from the fulcrum. How far from the fulcrum must a 100-lb effort be applied to balance the lever?

Answer: 6 feet

Using the lever principle: Load × Load arm = Effort × Effort arm → 300 × 2 = 100 × x → x = 6 feet.

Which pulley arrangement provides NO mechanical advantage but is still useful in practical applications?

Answer: Fixed pulley

A single fixed pulley has a mechanical advantage of 1 (no force reduction) but changes the direction of force, which is practically useful.

In a gear train where the driver has 30 teeth and the driven gear has 15 teeth, the output shaft rotates at what speed relative to the input?

Answer: Twice the input speed

Gear ratio = driver teeth / driven teeth = 30/15 = 2, so the driven gear spins twice as fast as the driver.