ASVAB Mechanical Comprehension Practice Test 357977 Results

Your Results Global Average
Questions 5 5
Correct 0 2.74
Score 0% 55%

Review

1 If you have a gear train with three gears, the first with 22 teeth, the second with 12 teeth, and the third with 2 teeth, what is its mechanical advantage?
51% Answer Correctly
16.5
3.7
11
12.5

Solution

The mechanical advantage of a gear train is its gear ratio. The gear ratio (Vr) 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 three gears so the equation becomes:

Vr = \( \frac{N_1}{N_2} \) \( \frac{N_2}{N_3} \) = \( \frac{22}{12} \) \( \frac{12}{2} \) = \( \frac{22}{2} \) = 11


2

Which of the following will increase the mechanical advantage of this inclined plane?

59% Answer Correctly

increase the force acting at the blue arrow

shorten the ramp

lengthen the ramp

lower the force acting at the blue arrow


Solution

The mechanical advantage (MA) of an inclined plane is the effort distance divided by the resistance distance. In order to increase mechanical advantage, this ratio must increase which means making the effort distance longer and this can be accomplished by lengthening the length of the ramp.


3

Which of the following is not a characteristic of a ceramic?

61% Answer Correctly

chemically stable

low density

low corrosive action

high melting point


Solution

Ceramics are mixtures of metallic and nonmetallic elements that withstand exteme thermal, chemical, and pressure environments. They have a high melting point, low corrosive action, and are chemically stable. Examples include rock, sand, clay, glass, brick, and porcelain.


4

Specific gravity is a comparison of the density of an object with the density of:

57% Answer Correctly

carbon

oil

air

water


Solution

Specific gravity is the ratio of the density of equal volumes of a substance and water and is measured by a hyrdometer.


5

Which of the following statements about this pulley configuration is false?

48% Answer Correctly

Only multiplies the effort force

Changes the direction of and multiplies the effort force

This is a block and tackle pulley configuration

Mechanical advantage is the number of ropes that support the resistance


Solution

A block and tackle is a combination of one or more fixed pulleys and one or more movable pulleys where the fixed pulleys change the direction of the effort force and the movable pulleys multiply it. The mechanical advantage is equal to the number of times the effort force changes direction and can be increased by adding more pulley wheels to the system. An easy way to find the mechanical advantage of a block and tackle pulley system is to count the number of ropes that support the resistance.