ASVAB Mechanical Comprehension Practice Test 948146 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.82
Score	0%	56%

Review

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

61% Answer Correctly

	low density
	low corrosive action
	chemically stable
	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.

Which of the following represents the force a surface exerts when an object presses against it?

48% Answer Correctly

	mass
	normal force
	friction
	counter force

Solution

Normal force (F_N) represents the force a surface exerts when an object presses against it.

3 If 45 lbs. of force is applied 5 ft. from the fulcrum at the blue arrow and the green box is 2 ft. from the fulcrum, how much would the green box have to weigh to balance the lever?

62% Answer Correctly

	450 lbs.
	0 lbs.
	225 lbs.
	112.5 lbs.

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:

R_ad_a = R_bd_b

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 R_a, our missing value, and plugging in our variables yields:

R_a = \( \frac{R_bd_b}{d_a} \) = \( \frac{45 lbs. \times 5 ft.}{2 ft.} \) = \( \frac{225 ft⋅lb}{2 ft.} \) = 112.5 lbs.

4 How much work can a 5 hp engine do in 7 seconds?

52% Answer Correctly

	2 ft⋅lb
	1 ft⋅lb
	19250 ft⋅lb
	0 ft⋅lb

Solution

Horsepower (hp) is a common measure of power output for complex machines. By definition, a 1 hp machine does 550 ft⋅lb of work in 1 second: 1 hp = 550 ft⋅lb/s. Substituting the variables for this problem gives us:
\( W = 5 hp \times 550 \frac{ft⋅lb}{s} \times 7s = 19250 ft⋅lb \)

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

60% Answer Correctly

	non-uniformly distributed load
	dynamic load
	impact load
	static uniformly distributed 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.