ASVAB Mechanical Comprehension Practice Test 283232 Results

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

Review

1 What is the efficiency of a machine has work input of 160 ft⋅lb and work output of 112 ft⋅lb?

68% Answer Correctly

	35%
	0%
	280%
	70%

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:
\( Efficiency = \frac{Work_{out}}{Work_{in}} \times 100 \) \( = \frac{112 ft⋅lb}{160 ft⋅lb} \times 100 \) \( = 70% \) %

Two gears are connected and the smaller gear drives the larger gear. The speed of rotation will __________ and the torque will __________.

61% Answer Correctly

	increase, decrease
	decrease, decrease
	increase, increase
	decrease, increase

Solution

Connected gears of different numbers of teeth are used together to change the rotational speed and torque of the input force. If the smaller gear drives the larger gear, the speed of rotation will be reduced and the torque will increase. If the larger gear drives the smaller gear, the speed of rotation will increase and the torque will be reduced.

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

49% Answer Correctly

	counter force
	normal force
	mass
	friction

Solution

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

Which of the following will increase the mechanical advantage of this inclined plane?

59% Answer Correctly

	lower the force acting at the blue arrow
	lengthen the ramp
	shorten the ramp
	increase the force acting at the blue arrow

Solution

The mechanical advantage (MA) of an inclined plane is the effort distance divided by the resistance distance. In order to increase mechanical advantage, this ratio must increase which means making the effort distance longer and this can be accomplished by lengthening the length of the ramp.

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

58% Answer Correctly

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

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