ASVAB Mechanical Comprehension Practice Test 478213 Results

Your Results Global Average
Questions 5 5
Correct 0 3.25
Score 0% 65%

Review

1

What type of load creates different stresses at different locations on a structure?

60% Answer Correctly

impact load

static uniformly distributed 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.


2 If you have a gear train with two gears, the first with 32 teeth and the second with 16 teeth, how many revolutions does the second gear make for each revolution of the first gear?
77% Answer Correctly
-2
4
5
2

Solution

The gear ratio (Vr) of a gear train is the product of the gear ratios between the pairs of meshed gears. Let N represent the number of teeth for each gear:

Vr = \( \frac{N_1}{N_2} \) \( \frac{N_2}{N_3} \) \( \frac{N_3}{N_4} \) ... \( \frac{N_n}{N_{n+1}} \)

In this problem, we have only two gears so the equation becomes:

Vr = \( \frac{N_1}{N_2} \) = \( \frac{32}{16} \) = 2


3 If the green box weighs 65 lbs. and 30 lbs. of force is applied 5 ft. from the fulcrum at the blue arrow, how far from the fulcrum would the green box need to be placed to balance the lever?
55% Answer Correctly
4.62 ft.
2.31 ft.
9.23 ft.
1.15 ft.

Solution

To balance this lever the torques at the green box and the blue arrow must be equal. Torque is weight x distance from the fulcrum so the equation for equilibrium is:

Rada = Rbdb

where a represents the green box and b the blue arrow, R is resistance (weight/force) and d is the distance from the fulcrum.

Solving for da, our missing value, and plugging in our variables yields:

da = \( \frac{R_bd_b}{R_a} \) = \( \frac{30 lbs. \times 5 ft.}{65 lbs.} \) = \( \frac{150 ft⋅lb}{65 lbs.} \) = 2.31 ft.


4

A wedge is most similar to what other type of simple machine?

70% Answer Correctly

first-class lever

second-class lever

inclined plane

third-class lever


Solution

The wedge is a moving inclined plane that is used to lift, hold, or break apart an object. A wedge converts force applied to its blunt end into force perpendicular to its inclined surface. In contrast to a stationary plane where force is applied to the object being moved, with a wedge the object is stationary and the force is being applied to the plane. Examples of a wedge include knives and chisels.


5

According to Boyle's law, for a fixed amount of gas kept at a fixed temperature, which of the following are inversely proportional?

63% Answer Correctly

density, volume

pressure, volume

pressure, density

volume, mass


Solution

Boyle's law states that "for a fixed amount of an ideal gas kept at a fixed temperature, pressure and volume are inversely proportional".