WTMA Wheels, Axles, and Rotation 3

Question 1

A compound gear train has three gears in sequence: Gear 1 (40 teeth) drives Gear 2 (10 teeth), which shares an axle with Gear 3 (30 teeth), which drives Gear 4 (15 teeth). What is the overall speed ratio (Gear 4 speed / Gear 1 speed)?

Accepted Answer

8:1

Answer

Stage 1 ratio: 40/10 = 4; Stage 2 ratio: 30/15 = 2; overall = 4 × 2 = 8, so Gear 4 spins 8 times faster than Gear 1.

Question 2

A crossed belt connects two pulleys. If the driving pulley rotates clockwise, the driven pulley rotates:

Accepted Answer

Counterclockwise

Answer

A crossed belt reverses the direction of rotation, so a clockwise driver produces counterclockwise motion in the driven pulley.

Question 3

Which change would MOST increase the torque output of a wheel-and-axle system when effort is applied at the wheel?

Accepted Answer

Increasing the wheel's radius

Answer

Torque output increases when the effort arm (wheel radius) is larger relative to the load arm (axle radius), so increasing wheel radius boosts mechanical advantage.

Question 4

A bicycle has a front chainring with 48 teeth and a rear sprocket with 16 teeth. How many times does the rear wheel rotate for each pedal revolution?

Accepted Answer

3

Answer

Speed ratio = driver teeth / driven teeth = 48/16 = 3, so the rear wheel makes 3 revolutions per pedal revolution.

Question 5

A wheel rolling uphill loses speed compared to rolling on flat ground (same force applied). This is primarily because:

Accepted Answer

Gravity adds a resisting force component along the slope

Answer

On an incline, gravity acts against motion along the slope, requiring additional force to maintain speed, which slows the wheel if force is unchanged.

WTMA - Wiesen Test of Mechanical Aptitude Practice Test

WTMA - Wiesen Test of Mechanical Aptitude Practice Test

WTMA Wheels, Axles, and Rotation 3