WTMA Wheels, Axles, and Rotation 4

Question 1

A flywheel stores energy by spinning at high speed. Which property MOST determines how much energy it can store?

Accepted Answer

Its rotational speed and mass distribution

Answer

Rotational kinetic energy depends on both the moment of inertia (how mass is distributed) and the square of rotational speed.

Question 2

Gear A (driver, 12 teeth) meshes directly with Gear B (36 teeth). Gear A rotates at 900 RPM. What is Gear B's speed?

Accepted Answer

300 RPM

Answer

Speed of Gear B = (teeth of A / teeth of B) × speed of A = (12/36) × 900 = 300 RPM.

Question 3

A hand truck (dolly) has small wheels. Replacing them with larger-diameter wheels would primarily:

Accepted Answer

Make it easier to roll over obstacles and reduce rolling resistance

Answer

Larger wheels have a higher ratio of radius to obstacle height, allowing them to roll over bumps more easily, and larger wheels generally have lower rolling resistance.

Question 4

In a clock, the minute hand completes one revolution per hour. The hour hand completes one revolution every 12 hours. What is the gear ratio between the mechanisms driving each hand?

Accepted Answer

12:1

Answer

The minute hand turns 12 times for every 1 turn of the hour hand, so the gear ratio is 12:1.

Question 5

A wheel spins at constant speed. A point on the outer rim of the wheel compared to a point halfway to the center has:

Accepted Answer

Twice the linear speed

Answer

Linear (tangential) speed = angular speed × radius; at twice the radius, the rim point travels twice the linear speed.

WTMA - Wiesen Test of Mechanical Aptitude Practice Test

WTMA - Wiesen Test of Mechanical Aptitude Practice Test

WTMA Wheels, Axles, and Rotation 4