ASVAB Mechanical Comprehension Practice Test 692464 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.91
Score	0%	58%

Review

1 If the radius of the axle is 7 and the radius of the wheel is 8, what is the mechanical advantage of this wheel and axle configuration?

36% Answer Correctly

	7
	1
	1
	-1

Solution

The mechanical advantage of a wheel and axle lies in the difference in radius between the inner (axle) wheel and the outer wheel. But, this mechanical advantage is only realized when the input effort and load are applied to different wheels. Applying both input effort and load to the same wheel results in a mechanical advantage of 1.

Sam can do 50 ft. lb. of work in 2 minutes and 5 seconds. What would Sam have to do to increase his power output?

64% Answer Correctly

	do the work in 2 minutes
	do 100 ft. lb. of work in 4 minutes 12 seconds
	do 25 ft. lb. of work in 2 minutes 5 seconds
	do the work in 3 minutes

Solution

Power is the rate of doing work or \(\frac{W}{t}\). To increase power, increase the work being done in the same amount of time or do the same amount of work in less time.

The mass of an object correlates to the size of the object but ultimately depends on:

66% Answer Correctly

	gravity
	the object's potential energy
	the object's weight
	the object's density

Solution

Mass is a measure of the amount of matter in an object. In general, larger objects have larger mass than smaller objects but mass ultimately depends on how compact (dense) a substance is.

4 A 330 lb. barrel is rolled up a 5 ft. ramp to a platform that's 5 ft. tall. What effort is required to move the barrel?

53% Answer Correctly

	332 lbs.
	330 lbs.
	363 lbs.
	331.5 lbs.

Solution

This problem describes an inclined plane and, for an inclined plane, the effort force multiplied by the effort distance equals the resistance force multipied by the resistance distance:

F_ed_e = F_rd_r

Plugging in the variables from this problem yields:

F_e x 5 ft. = 330 lbs. x 5 ft.
F_e = \( \frac{1650 ft⋅lb}{5 ft.} \) = 330 lbs.

Which of these is the formula for kinetic energy?

67% Answer Correctly

	\(KE = {1 \over 2}mv^2\)
	\(KE = mgh\)
	\(KE = {m \over v^2 }\)
	\(KE = {1 \over 2}mh^2\)

Solution

Kinetic energy is the energy of movement and is a function of the mass of an object and its speed: \(KE = {1 \over 2}mv^2\) where m is mass in kilograms, v is speed in meters per second, and KE is in joules. The most impactful quantity to kinetic energy is velocity as an increase in mass increases KE linearly while an increase in speed increases KE exponentially.