ASVAB Mechanical Comprehension Practice Test 649328 Results

Your Results Global Average
Questions 5 5
Correct 0 2.90
Score 0% 58%

Review

1

The science that deals with motion and the forces that produce motion is called which of the following?

57% Answer Correctly

mechanics

physics

engineering

aeronautics


Solution

Mechanics deals with motion and the forces that produce motion.


2

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

61% Answer Correctly

low corrosive action

chemically stable

low density

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.


3

Which of these will have the most impact on the kinetic energy of an object?

54% Answer Correctly

its speed

its weight

its direction

its mass


Solution

Kinetic energy is the energy of movement and is a function of the mass of an object and its speed: \(KE = {1 \over 2}mv^2\) where m is mass in kilograms, v is speed in meters per second, and KE is in joules. The most impactful quantity to kinetic energy is velocity as an increase in mass increases KE linearly while an increase in speed increases KE exponentially.


4

The mechanical advantage of a block and tackle is equal to which of the following?

69% Answer Correctly

the number of pulleys

the number of loads

the number of input forces

the number of connecting ropes


Solution

Two or more pulleys used together constitute a block and tackle which, unlike a fixed pulley, does impart mechanical advantage as a function of the number of pulleys that make up the arrangement.  So, for example, a block and tackle with three pulleys would have a mechanical advantage of three.


5 If you have a gear train with three gears, the first with 30 teeth, the second with 14 teeth, and the third with 2 teeth, what is its mechanical advantage?
51% Answer Correctly
22.5
11
15
45

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 = \( \frac{N_1}{N_2} \) \( \frac{N_2}{N_3} \) = \( \frac{30}{14} \) \( \frac{14}{2} \) = \( \frac{30}{2} \) = 15