ASVAB Mechanical Comprehension Practice Test 632505 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.03
Score	0%	61%

Review

The mechanical advantage of a third class lever is always:

37% Answer Correctly

	equal to one
	not equal to one
	greater than one
	less than one

Solution

A third class lever is designed to multiply distance and speed at the expense of effort force. Because the effort force is greater than the resistance, the mechanical advantage of a third class lever is always less than one.

An example of a third class lever is a broom. The fulcrum is at your hand on the end of the broom, the effort force is your other hand in the middle, and the resistance is at the bottom bristles. The effort force of your hand in the middle multiplies the distance and speed of the bristles at the bottom but at the expense of producing a brushing force that's less than the force you're applying with your hand.

2 If you lift a 49 lbs. rock 50 ft. from the ground, how much work have you done?

71% Answer Correctly

	0 ft⋅lb
	None of these is correct
	4900 ft⋅lb
	2450 ft⋅lb

Solution

Work is force times distance. In this case, the force is the weight of the rock so:
\( W = F \times d \)
\( W = 49 \times 50 \)
\( W = 2450 \)

Collinear forces:

72% Answer Correctly

	are unrelated to each other
	act in a common plane
	act along the same line of action
	pass through a common point

Solution

Collinear forces act along the same line of action, concurrent forces pass through a common point and coplanar forces act in a common plane.

4 If the radius of the axle is 7 and the radius of the wheel is 10, what is the mechanical advantage of this wheel and axle configuration?

41% Answer Correctly

	7
	0.7
	1.43
	3

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 7 and the output radius (where the resistance is being applied) is 10 for a mechanical advantage of \( \frac{7}{10} \) = 0.7

Potential energy is energy that has the potential to be converted into what?

80% Answer Correctly

	work
	heat
	kinetic energy
	power

Solution

Potential energy is the energy of an object by virtue of its position relative to other objects. It is energy that has the potential to be converted into kinetic energy.