ASVAB Mechanical Comprehension Practice Test 391329 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.39
Score	0%	68%

Review

1 A mass of air has a pressure of 9.0 psi and a volume of 45 ft.³. If the air is compressed to a new volume of 20 ft.³, what is the new pressure?

56% Answer Correctly

	22.3 psi
	20.3 psi
	16.3 psi
	18.2 psi

Solution

According to Boyle's Law, pressure and volume are inversely proportional:

\( \frac{P_1}{P_2} \) = \( \frac{V_2}{V_1} \)

In this problem, V₂ = 20 ft.³, V₁ = 45 ft.³ and P₁ = 9.0 psi. Solving for P₂:

P₂ = \( \frac{P_1}{\frac{V_2}{V_1}} \) = \( \frac{9.0 psi}{\frac{20 ft.^3}{45 ft.^3}} \) = 20.3 psi

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

61% Answer Correctly

	chemically stable
	high melting point
	low density
	low corrosive action

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.

Collinear forces:

72% Answer Correctly

	pass through a common point
	act along the same line of action
	are unrelated to each other
	act in a common plane

Solution

Collinear forces act along the same line of action, concurrent forces pass through a common point and coplanar forces act in a common plane.

Which of the following surfaces would have the lowest coefficient of friction?

85% Answer Correctly

	tile
	concrete
	ice
	leather

Solution

Coefficient of friction (μ) represents how much two materials resist sliding across each other. Smooth surfaces like ice have low coefficients of friction while rough surfaces like concrete have high μ.

5 If the green arrow in this diagram represents 300 ft⋅lb of work, how far will the box move if it weighs 60 pounds?

72% Answer Correctly

	1 ft.
	5 ft.
	10 ft.
	12 ft.

Solution

The Law of Work states that the work put into a machine is equal to the work received from the machine under ideal conditions. In equation form, that's:

W_in = W_out
F_effort x d_effort = F_resistance x d_resistance

In this problem, the effort work is 300 ft⋅lb and the resistance force is 60 lbs. and we need to calculate the resistance distance:

W_in = F_resistance x d_resistance
300 ft⋅lb = 60 lbs. x d_resistance
d_resistance = \( \frac{300ft⋅lb}{60 lbs.} \) = 5 ft.