ASVAB Mechanical Comprehension Practice Test 487523 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.44
Score	0%	69%

Review

1 If this lever is in equilibrium with an effort force of 15.0 ft. lb. at the blue arrow and a resistance force of 3 ft. lb. at the green box, what is its mechanical advantage?

48% Answer Correctly

	1.7
	0.3
	0.2
	0.4

Solution

Mechanical advantage (MA) is the ratio by which effort force relates to resistance force. If both forces are known, calculating MA is simply a matter of dividing resistance force by effort force:

MA = \( \frac{F_r}{F_e} \) = \( \frac{3 ft.}{15.0 ft.} \) = 0.2

In this case, the mechanical advantage is less than one meaning that each unit of effort force results in just 0.2 units of resistance force. However, a third class lever like this isn't designed to multiply force like a first class lever. A third class lever is designed to multiply distance and speed at the resistance by sacrificing force at the resistance. Different lever styles have different purposes and multiply forces in different ways.

2 If you have a gear train with two gears, the first with 28 teeth and the second with 12 teeth, how many revolutions does the second gear make for each revolution of the first gear?

77% Answer Correctly

	2.1
	2.6
	2.3
	11.3

Solution

The gear ratio (V_r) of a gear train is the product of the gear ratios between the pairs of meshed gears. Let N represent the number of teeth for each gear:

V_r = \( \frac{N_1}{N_2} \) \( \frac{N_2}{N_3} \) \( \frac{N_3}{N_4} \) ... \( \frac{N_n}{N_{n+1}} \)

In this problem, we have only two gears so the equation becomes:

V_r = \( \frac{N_1}{N_2} \) = \( \frac{28}{12} \) = 2.3

3 If the green arrow in this diagram represents 260 ft⋅lb of work, how far will the box move if it weighs 130 pounds?

72% Answer Correctly

	65 ft.
	0 ft.
	2 ft.
	8 ft.

Solution

The Law of Work states that the work put into a machine is equal to the work received from the machine under ideal conditions. In equation form, that's:

W_in = W_out
F_effort x d_effort = F_resistance x d_resistance

In this problem, the effort work is 260 ft⋅lb and the resistance force is 130 lbs. and we need to calculate the resistance distance:

W_in = F_resistance x d_resistance
260 ft⋅lb = 130 lbs. x d_resistance
d_resistance = \( \frac{260ft⋅lb}{130 lbs.} \) = 2 ft.

When it comes to force, mass and acceleration have what kind of relationship?

66% Answer Correctly

	logarithmic
	exponential
	inverse
	linear

Solution

Newton's Second Law of Motion states that "The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object." This Law describes the linear relationship between mass and acceleration when it comes to force and leads to the formula F = ma or force equals mass multiplied by rate of acceleration.

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

80% Answer Correctly

	heat
	kinetic energy
	work
	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.