FREE AFCT Mechanical Comprehension Questions and Answers

Question 1

In the gear train shown, Gear 1 turns clockwise. In which direction will Gear 3 turn?

Accepted Answer

Clockwise.

Answer

When two external gears mesh, they turn in opposite directions. Gear 1 turns clockwise, so Gear 2 (the idler gear) must turn counter-clockwise. Since Gear 2 turns counter-clockwise, Gear 3, which meshes with it, must turn in the opposite direction, which is clockwise.

Question 2

To lift a heavy object with a lever and fulcrum, where should the fulcrum be placed to use the least amount of effort?

Accepted Answer

Closer to the heavy object.

Answer

According to the law of the lever, placing the fulcrum closer to the load (the heavy object) increases the mechanical advantage. This means a smaller effort force is required to lift the load because the distance over which the effort is applied is longer than the distance the load is lifted.

Question 3

In a hydraulic lift system, a small amount of force is applied to a small piston. What is the effect on the larger piston?

Accepted Answer

A larger force is exerted over a smaller distance.

Answer

This scenario demonstrates Pascal's Principle, which states that pressure applied to an enclosed fluid is transmitted undiminished throughout the fluid. Because pressure equals force divided by area (P=F/A), a small force on a small area creates a certain pressure. This same pressure acting on a larger area on the other piston generates a much larger output force, though it moves a shorter distance.

Question 4

A ball is being swung in a circle on the end of a string. If the string suddenly breaks, in which direction will the ball travel?

Accepted Answer

It will fly off in a straight line tangent to the circle at the point of release.

Answer

The string provides the centripetal force needed to keep the ball moving in a circle. When the string breaks, this force disappears. Due to inertia, the ball will continue to travel in the direction it was moving at that instant, which is a straight line tangent to the circular path.

Question 5

Which of the following pulley systems provides the greatest mechanical advantage and makes it easiest to lift the 100lb weight?

Accepted Answer

Two fixed pulleys and two movable pulleys.

Answer

The mechanical advantage of a pulley system is generally equal to the number of rope segments supporting the load. A system with two fixed and two movable pulleys will have four supporting rope segments, providing a 4:1 mechanical advantage, which is greater than the other options and requires the least effort to lift the weight.

(AFCT) Armed Forces Classification Test Practice Test

(AFCT) Armed Forces Classification Test Practice Test

FREE AFCT Mechanical Comprehension Questions and Answers