ASVAB Mechanical Comprehension Practice Test 515197 Results

Your Results Global Average
Questions 5 5
Correct 0 2.93
Score 0% 59%

Review

1 If the radius of the axle is 3 and the radius of the wheel is 6, what is the mechanical advantage of this wheel and axle configuration?
52% Answer Correctly
-3
3
2.0
6

Solution

The mechanical advantage of a wheel and axle is the input radius divided by the output radius:

MA = \( \frac{r_i}{r_o} \)

In this case, the input radius (where the effort force is being applied) is 6 and the output radius (where the resistance is being applied) is 3 for a mechanical advantage of \( \frac{6}{3} \) = 2.0


2

The mechanical advantage of a wheel and axle is equal to the:

61% Answer Correctly

difference in the lengths of the axles

difference in the diameters of the wheels

ratio of the diameters of the wheels

length of the axle


Solution

A wheel and axle uses two different diameter wheels mounted to a connecting axle. Force is applied to the larger wheel and large movements of this wheel result in small movements in the smaller wheel. Because a larger movement distance is being translated to a smaller distance, force is increased with a mechanical advantage equal to the ratio of the diameters of the wheels. An example of a wheel and axle is the steering wheel of a car.


3

Boyle's law defines the relationship between pressure and volume as:

57% Answer Correctly

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

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

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

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


Solution

Boyle's law states that "for a fixed amount of an ideal gas kept at a fixed temperature, pressure and volume are inversely proportional". Expressed as a formula, that's \(\frac{P_1}{P_2} = \frac{V_2}{V_1}\)


4

What's the first gear in a gear train called?

57% Answer Correctly

driven gear

driver gear

idler gear

input gear


Solution

A gear train is two or more gears linked together. Gear trains are designed to increase or reduce the speed or torque outpout of a rotating system or change the direction of its output. The first gear in the chain is called the driver and the last gear in the chain the driven gear with the gears between them called idler gears.


5 What is the efficiency of a machine has work input of 250 ft⋅lb and work output of 187 ft⋅lb?
67% Answer Correctly
75%
150%
37%
0%

Solution
Due to friction, a machine will never be able to utilize 100% of its work input. A certain percentage of that input will be lost in overcoming friction within the machine. Effeciency is a measure of how much of a machine's work input can be turned into useful work output and is calculated by dividing work output by work input and multiplying the result by 100:
\( Efficiency = \frac{Work_{out}}{Work_{in}} \times 100 \) \( = \frac{187 ft⋅lb}{250 ft⋅lb} \times 100 \) \( = 75% \) %