ASVAB Mechanical Comprehension Practice Test 141690 Results

Your Results Global Average
Questions 5 5
Correct 0 2.69
Score 0% 54%

Review

1

What's the last gear in a gear train called?

38% Answer Correctly

idler gear

driver gear

output gear

driven gear
Solution

A gear train is two or more gears linked together. Gear trains are designed to increase or reduce the speed or torque outpout of a rotating system or change the direction of its output. The first gear in the chain is called the driver and the last gear in the chain the driven gear with the gears between them called idler gears.

2

Which of the following is not true of a  first-class lever?

51% Answer Correctly

increases distance

decreases distance

increases force

changes the direction of force
Solution

A first-class lever is used to increase force or distance while changing the direction of the force. The lever pivots on a fulcrum and, when a force is applied to the lever at one side of the fulcrum, the other end moves in the opposite direction. The position of the fulcrum also defines the mechanical advantage of the lever. If the fulcrum is closer to the force being applied, the load can be moved a greater distance at the expense of requiring a greater input force. If the fulcrum is closer to the load, less force is required but the force must be applied over a longer distance. An example of a first-class lever is a seesaw / teeter-totter.

3

What type of load acts on a relatively small area of a structure?

74% Answer Correctly

impact load

concentrated load

non-uniformly distributed load

dynamic load
Solution

A concentrated load acts on a relatively small area of a structure, a static uniformly distributed load doesn't create specific stress points or vary with time, a dynamic load varies with time or affects a structure that experiences a high degree of movement, an impact load is sudden and for a relatively short duration and a non-uniformly distributed load creates different stresses at different locations on a structure.

4

A shovel is an example of which class of lever?

56% Answer Correctly

third

a shovel is not a lever

second

first
Solution

A third-class lever is used to increase distance traveled by an object in the same direction as the force applied. The fulcrum is at one end of the lever, the object at the other, and the force is applied between them. This lever does not impart a mechanical advantage as the effort force must be greater than the load but does impart extra speed to the load. Examples of third-class levers are shovels and tweezers.

5 A 380 lb. barrel is rolled up a 7 ft. ramp to a platform that's 4 ft. tall. What effort is required to move the barrel?
53% Answer Correctly
218.6 lbs.
217.1 lbs.
238.9 lbs.
195.4 lbs.
Solution

This problem describes an inclined plane and, for an inclined plane, the effort force multiplied by the effort distance equals the resistance force multipied by the resistance distance:

Fede = Frdr

Plugging in the variables from this problem yields:

Fe x 7 ft. = 380 lbs. x 4 ft.
Fe = \( \frac{1520 ft⋅lb}{7 ft.} \) = 217.1 lbs.