Mechanical Aptitude Mechanical Aptitude Levers, Pulleys, and Gears 4

Question 1

A first-class lever has the fulcrum exactly in the middle. What is its mechanical advantage?

Accepted Answer

1

Answer

When the fulcrum is centered, the effort arm equals the resistance arm, giving a mechanical advantage of exactly 1.

Question 2

Helical gears are preferred over spur gears for high-speed applications primarily because they:

Accepted Answer

Engage more gradually, reducing noise and vibration

Answer

Helical gears have angled teeth that engage progressively, spreading the load and reducing the noise and vibration common in spur gears.

Question 3

In a pulley system, if you pull 6 feet of rope to raise a load by 2 feet, what is the mechanical advantage?

Accepted Answer

3

Answer

Mechanical advantage = distance effort moves ÷ distance load moves = 6 ÷ 2 = 3.

Question 4

A pair of scissors is an example of which lever class?

Accepted Answer

First class

Answer

Scissors are first-class levers because the fulcrum (pivot pin) is between the effort (finger handles) and the load (blades cutting material).

Question 5

A worm gear system provides a high gear ratio and:

Accepted Answer

Is typically non-reversible — the worm can drive the gear but not vice versa

Answer

Worm gears are self-locking in most configurations because the high friction prevents the wheel from backdriving the worm.

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