ASVAB Mechanical Comprehension Practice Test 851764 Results

Your Results Global Average
Questions 5 5
Correct 0 2.83
Score 0% 57%

Review

1

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

77% Answer Correctly

marble

ice

steel

concrete
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.

2 A mass of air has a pressure of 12.0 psi and a volume of 60 ft.3. If the air is compressed to a new volume of 40 ft.3, what is the new pressure?
56% Answer Correctly
21 psi
19.8 psi
9 psi
18 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 = 40 ft.3, V1 = 60 ft.3 and P1 = 12.0 psi. Solving for P2:

P2 = \( \frac{P_1}{\frac{V_2}{V_1}} \) = \( \frac{12.0 psi}{\frac{40 ft.^3}{60 ft.^3}} \) = 18 psi

3

A wedge converts force applied to its blunt end into force __________ its inclined surface.

57% Answer Correctly

parallel to

perpendicular to

opposite to

along
Solution

The wedge is a moving inclined plane that is used to lift, hold, or break apart an object. A wedge converts force applied to its blunt end into force perpendicular to its inclined surface. In contrast to a stationary plane where force is applied to the object being moved, with a wedge the object is stationary and the force is being applied to the plane. Examples of a wedge include knives and chisels.

4

Depending on where you apply effort and resistance, the wheel and axle can multiply:

45% Answer Correctly

power or distance

force or distance

speed or power

force or speed
Solution

If you apply the resistance to the axle and the effort to the wheel, the wheel and axle will multiply force and if you apply the resistance to the wheel and the effort to the axle, it will multiply speed.

5 If A = 9 ft., B = 3 ft., C = 4 ft., the green box weighs 35 lbs. and the blue box weighs 55 lbs., what does the orange box have to weigh for this lever to balance?
44% Answer Correctly
112.5 lbs.
0 lbs.
37.5 lbs.
150 lbs.
Solution
In order for this lever to balance, the torque acting on each side of the fulrum must be equal. So, the torque produced by A must equal the torque produced by B and C. Torque is weight x distance from the fulcrum which means that the following must be true for the lever to balance:

fAdA = fBdB + fCdC

For this problem, this equation becomes:

35 lbs. x 9 ft. = 55 lbs. x 3 ft. + fC x 4 ft.

315 ft. lbs. = 165 ft. lbs. + fC x 4 ft.

fC = \( \frac{315 ft. lbs. - 165 ft. lbs.}{4 ft.} \) = \( \frac{150 ft. lbs.}{4 ft.} \) = 37.5 lbs.