ASVAB Mechanical Comprehension Practice Test 914374 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.87
Score	0%	77%

Review

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

86% Answer Correctly

	leather
	concrete
	ice
	tile

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.

When all forces acting on a system cancel each other out, this is called:

81% Answer Correctly

	potential energy
	rest
	equilibrium
	stasis

Solution

When a system is stable or balanced (equilibrium) all forces acting on the system cancel each other out. In the case of torque, equilibrium means that the sum of the anticlockwise moments about a center of rotation equal the sum of the clockwise moments.

3 What is the mechanical advantage of this inclined plane if the length of the ramp is 32 ft. and the height of the green box is 4 ft.?

82% Answer Correctly

	16
	7.2
	8
	3

Solution

The mechanical advantage (MA) of an inclined plane is the effort distance divided by the resistance distance. In this case, the effort distance is the length of the ramp and the resistance distance is the height of the green box:

MA = \( \frac{d_e}{d_r} \) = \( \frac{32 ft.}{4 ft.} \) = 8

4 A = 5 ft., the green box weighs 30 lbs., and the blue box weighs 75 lbs. What does distance B need to be for this lever to balance?

65% Answer Correctly

	2 ft.
	4 ft.
	15 ft.
	0.5 ft.

Solution

In order for this lever to balance, the torque acting on side A must equal the torque acting on side B. Torque is weight x distance from the fulcrum which means that the following must be true for the lever to balance:

f_Ad_A = f_Bd_B

For this problem, the equation becomes:

30 lbs. x 5 ft. = 75 lbs. x d_B

d_B = \( \frac{30 \times 5 ft⋅lb}{75 lbs.} \) = \( \frac{150 ft⋅lb}{75 lbs.} \) = 2 ft.

Hydraulics is the transmission of force through the use of which of the following?

73% Answer Correctly

	gear systems
	torque
	liquids
	air pressure

Solution

Hydraulics is the transmission of force through the use of liquids. Liquids are especially suited for transferring force in complex machines because they compress very little and can occupy very small spaces. Hydraulic pressure is calculated by dividing force by the area over which it is applied: P = F/A where F is force in pounds, A is area in square inches, and the resulting pressure is in pounds per square inch (psi).