Bennett Mechanical Comprehension Practice Test 2026 – The Complete All-in-One Guide to Exam Success!

When the radius of a driving wheel in a belt system is increased, the speed of the belt actually decreases. This is due to the relationship between the radius of the wheel and the linear speed of the belt.

In a belt drive system, the driving wheel turns, and the belt moves along with it. The linear speed of the belt is determined by the rotational speed of the wheel and the radius of that wheel. Mathematically, the linear speed of the belt can be expressed as the product of the radius of the wheel and the angular speed (in radians per second). Therefore, if the radius increases while the angular speed remains constant, the linear speed of the belt must decrease to maintain the balance, as the circumference of the larger wheel means that it takes more time to complete one rotation due to covering more distance.

This relationship indicates that for a constant angular velocity, an increase in the radius leads to a decrease in the belt's speed. The other options do not accurately reflect the physical principles at play in a belt system.