ASVAB Mechanical Comprehension Practice Test 298362 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.25
Score	0%	65%

Review

1 What's the mechanical advantage of a wedge that's 5 inches wide and 30 inches long?

83% Answer Correctly

	6
	12
	5.4
	6.6

Solution

The mechanical advantage (MA) of a wedge is its length divided by its thickness:

MA = \( \frac{l}{t} \) = \( \frac{30 in.}{5 in.} \) = 6

Force of friction due to kinetic friction is __________ the force of friction due to static friction.

40% Answer Correctly

	lower than
	the same as
	higher than
	opposite

Solution

The formula for force of friction (F_f) is the same whether kinetic or static friction applies: F_{f =}μF_N. To distinguish between kinetic and static friction, μ_k and μ_s are often used in place of μ.

The mechanical advantage of connected gears is proportional to which characteristic of the gears?

73% Answer Correctly

	circumference
	diameter
	number of teeth
	speed

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 you lift a 7 lbs. rock 32 ft. from the ground, how much work have you done?

71% Answer Correctly

	224 ft⋅lb
	0 ft⋅lb
	-25 ft⋅lb
	4 ft⋅lb

Solution

Work is force times distance. In this case, the force is the weight of the rock so:
\( W = F \times d \)
\( W = 7 \times 32 \)
\( W = 224 \)

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

59% Answer Correctly

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