WTMA - Wiesen Test of Mechanical Aptitude Levers, Pulleys, and Gears Questions and Answers — Questions and Answers
Question 1: In the gear system shown, the driver gear (A) rotates clockwise. An idler gear (B) is placed between gear A and the driven gear (C). In which direction will gear C rotate?
- Counter-clockwise
- Clockwise (Correct answer)
- It will not rotate
- It will alternate directions
Correct answer: Clockwise
When two gears mesh directly, they rotate in opposite directions. Therefore, if driver gear A rotates clockwise, idler gear B will rotate counter-clockwise. Since gear B (counter-clockwise) meshes with gear C, gear C will rotate in the opposite direction, which is clockwise. The primary function of a single idler gear is to make the driver and driven gears rotate in the same direction.
Question 2: Which of the following lever classes always provides a mechanical advantage greater than 1, meaning the output force is always greater than the effort force?
- First-Class Lever
- Second-Class Lever (Correct answer)
- Third-Class Lever
- All classes can provide this advantage
Correct answer: Second-Class Lever
A second-class lever has the load (resistance) positioned between the fulcrum and the effort. This arrangement ensures the effort arm is always longer than the load arm, resulting in a mechanical advantage that is always greater than 1.
Question 3: A pulley system is set up to lift a heavy engine block. The system uses multiple pulleys, and the rope is threaded so that 4 rope segments are supporting the movable block attached to the engine. Ignoring friction, what is the mechanical advantage of this system?
- 2
- 3
- 4 (Correct answer)
- 8
Correct answer: 4
The ideal mechanical advantage (IMA) of a pulley system is equal to the number of rope segments directly supporting the load. In this scenario, there are 4 rope segments supporting the movable block, so the mechanical advantage is 4.
Question 4: A large gear with 60 teeth is driven by a small pinion gear with 20 teeth. If the small pinion gear rotates at 300 RPM, what will be the approximate speed of the large gear?
- 900 RPM
- 300 RPM
- 150 RPM
- 100 RPM (Correct answer)
Correct answer: 100 RPM
The gear ratio is calculated by dividing the number of teeth on the driven gear by the number of teeth on the driver gear (60/20 = 3:1). The speed of the output gear is the input speed divided by the gear ratio. Therefore, 300 RPM / 3 = 100 RPM. When a smaller gear drives a larger gear, speed is reduced and torque is increased.
Question 5: Imagine you are using a crowbar to lift a heavy rock. You place a small stone under the crowbar to act as a fulcrum. The rock is the load, and you push down on the end of the crowbar. This is an example of which class of lever?
- Second-Class Lever
- Third-Class Lever
- First-Class Lever (Correct answer)
- Fourth-Class Lever
Correct answer: First-Class Lever
In a first-class lever, the fulcrum is located between the effort (your push) and the load (the rock). A seesaw and a crowbar used in this manner are classic examples of first-class levers.
Question 6: In a pulley system, if you have to pull 10 feet of rope to lift a load 2 feet off the ground, what is the ideal mechanical advantage (IMA) of the system?
- 2
- 4
- 5 (Correct answer)
- 10
Correct answer: 5
The ideal mechanical advantage (IMA) can also be calculated as the ratio of the distance the effort moves to the distance the load moves. In this case, IMA = (Distance of effort) / (Distance of load) = 10 feet / 2 feet = 5.
WTMA - Wiesen Test of Mechanical Aptitude Levers, Pulleys, and Gears Questions and Answers
In the gear system shown, the driver gear (A) rotates clockwise.
An idler gear (B) is placed between gear A and the driven gear (C).
In which direction will gear C rotate?