ASVAB Mechanical Comprehension Practice Test 510977 Results

Your Results Global Average
Questions 5 5
Correct 0 3.42
Score 0% 68%

Review

1

Friction between two or more solid objects that are not moving relative to each other is called:

73% Answer Correctly

dynamic friction

gravitational friction

kinetic friction

static friction
Solution

Static friction is friction between two or more solid objects that are not moving relative to each other. An example is the friction that prevents a box on a sloped surface from sliding farther down the surface.

2

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

85% Answer Correctly

leather

concrete

tile

ice
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.

3

Gear ratio indicates which of the following about two connected gears?

59% Answer Correctly

work done

power conversion

mechanical advantage

efficiency
Solution

The mechanical advantage (amount of change in speed or torque) of connected gears is proportional to the number of teeth each gear has. Called gear ratio, it's the ratio of the number of teeth on the larger gear to the number of teeth on the smaller gear.  For example, a gear with 12 teeth connected to a gear with 9 teeth would have a gear ratio of 4:3.

4 If input effort is 700 ft⋅lb, what output effort will be produced by a machine with a mechanical advantage of 8?
79% Answer Correctly
5600 ft⋅lb
0ft⋅lb
1400ft⋅lb
87ft⋅lb
Solution
Mechanical advantage is the ratio of output force to input force and tells us by how many times a machine multiplies input effort. So, a machine with a mechanical advantage of 8 will multiply an input effort of 700 ft⋅lb by 8 to produce an output effort of 5600 ft⋅lb.
5 A mass of air has a pressure of 6.0 psi and a volume of 30 ft.3. If the air is compressed to a new volume of 5 ft.3, what is the new pressure?
56% Answer Correctly
18 psi
12 psi
36 psi
32 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 = 5 ft.3, V1 = 30 ft.3 and P1 = 6.0 psi. Solving for P2:

P2 = \( \frac{P_1}{\frac{V_2}{V_1}} \) = \( \frac{6.0 psi}{\frac{5 ft.^3}{30 ft.^3}} \) = 36 psi