Mechanical Aptitude Mechanical Aptitude Levers, Pulleys, and Gears 5

Question 1

A block-and-tackle system uses 3 movable pulleys and 3 fixed pulleys. What is the approximate mechanical advantage?

Accepted Answer

6

Answer

The mechanical advantage of a block-and-tackle equals the number of rope segments supporting the load, which is 6 in this configuration.

Question 2

A crowbar being used to pry open a crate is what class of lever?

Accepted Answer

First class

Answer

A crowbar is a first-class lever: the fulcrum (edge of crate) is between the effort (your hands pushing down) and the load (lid being lifted).

Question 3

Gear A has 12 teeth and rotates at 600 RPM. If Gear B meshes with Gear A and rotates at 200 RPM, how many teeth does Gear B have?

Accepted Answer

36 teeth

Answer

Using the gear ratio formula: Teeth B = (RPM A × Teeth A) ÷ RPM B = (600 × 12) ÷ 200 = 36 teeth.

Question 4

In a gear train, the gear that receives power from the engine is called the:

Accepted Answer

Driver gear

Answer

The driver gear (also called the input gear) is the one connected to the power source and initiates motion in the gear train.

Question 5

What happens to torque when a small gear drives a larger gear?

Accepted Answer

Torque increases

Answer

When a small driver gear turns a larger driven gear, speed decreases but torque increases proportionally (ignoring friction losses).

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