ASVAB Mechanical Comprehension Practice Test 740767 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.90
Score	0%	58%

Review

1 If you have a gear train with three gears, the first with 28 teeth, the second with 10 teeth, and the third with 4 teeth, what is its mechanical advantage?

51% Answer Correctly

	2
	10.5
	7
	6.3

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 = \( \frac{N_1}{N_2} \) \( \frac{N_2}{N_3} \) = \( \frac{28}{10} \) \( \frac{10}{4} \) = \( \frac{28}{4} \) = 7

A wedge converts force applied to its blunt end into force __________ its inclined surface.

57% Answer Correctly

	parallel to
	perpendicular to
	opposite to
	along

Solution

The wedge is a moving inclined plane that is used to lift, hold, or break apart an object. A wedge converts force applied to its blunt end into force perpendicular to its inclined surface. In contrast to a stationary plane where force is applied to the object being moved, with a wedge the object is stationary and the force is being applied to the plane. Examples of a wedge include knives and chisels.

Which of the following will increase the mechanical advantage of a second-class lever?

55% Answer Correctly

	move the fulcrum between the force and the object being lifted
	decrease the length of the lever
	move the object being lifted closer to the fulcrum
	move the object being lifted farther away from the fulcrum

Solution

A second-class lever is used to increase force on an object in the same direction as the force is applied. This lever requires a smaller force to lift a larger load but the force must be applied over a greater distance. The fulcrum is placed at one end of the lever and mechanical advantage increases as the object being lifted is moved closer to the fulcrum or the length of the lever is increased. An example of a second-class lever is a wheelbarrow.

4 If input effort is 800 ft⋅lb, what output effort will be produced by a machine with a mechanical advantage of 2?

79% Answer Correctly

	6400ft⋅lb
	3200ft⋅lb
	0ft⋅lb
	1600 ft⋅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 800 ft⋅lb by 2 to produce an output effort of 1600 ft⋅lb.

Which of the following is not a type of structural load?

49% Answer Correctly

	dead load
	wind load
	occupancy load
	live load

Solution

Dead load is the weight of the building and materials, live load is additional weight due to occupancy or use, snow load is the weight of accumulated snow on a structure and wind load is the force of wind pressures against structure surfaces.