ASVAB Mechanical Comprehension Practice Test 609924 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.94
Score	0%	59%

Review

1 If the radius of the axle is 5 and the radius of the wheel is 6, what is the mechanical advantage of this wheel and axle configuration?

41% Answer Correctly

	1.2
	5
	0.83
	1

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 5 and the output radius (where the resistance is being applied) is 6 for a mechanical advantage of \( \frac{5}{6} \) = 0.83

2 If input effort is 200 ft⋅lb, what output effort will be produced by a machine with a mechanical advantage of 2?

79% Answer Correctly

	100ft⋅lb
	200ft⋅lb
	400 ft⋅lb
	0ft⋅lb

Solution

Mechanical advantage is the ratio of output force to input force and tells us by how many times a machine multiplies input effort. So, a machine with a mechanical advantage of 2 will multiply an input effort of 200 ft⋅lb by 2 to produce an output effort of 400 ft⋅lb.

What type of load creates different stresses at different locations on a structure?

60% Answer Correctly

	non-uniformly distributed load
	dynamic load
	static uniformly distributed load
	impact load

Solution

A concentrated load acts on a relatively small area of a structure, a static uniformly distributed load doesn't create specific stress points or vary with time, a dynamic load varies with time or affects a structure that experiences a high degree of movement, an impact load is sudden and for a relatively short duration and a non-uniformly distributed load creates different stresses at different locations on a structure.

Normal force is generally equal to the __________ of an object.

62% Answer Correctly

	weight
	coefficient of friction
	mass
	density

Solution

Normal force arises on a flat horizontal surface in response to an object's weight pressing it down. Consequently, normal force is generally equal to the object's weight.

5 If you have a gear train with three gears, the first with 24 teeth, the second with 16 teeth, and the third with 4 teeth, what is its mechanical advantage?

52% Answer Correctly

	7.5
	5.4
	6
	12

Solution

The mechanical advantage of a gear train is its gear ratio. The gear ratio (V_r) 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 three gears so the equation becomes:

V_r = \( \frac{N_1}{N_2} \) \( \frac{N_2}{N_3} \) = \( \frac{24}{16} \) \( \frac{16}{4} \) = \( \frac{24}{4} \) = 6