ASVAB Mechanical Comprehension Practice Test 720843 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.32
Score	0%	66%

Review

1 If input effort is 600 ft⋅lb, what output effort will be produced by a machine with a mechanical advantage of 6?

79% Answer Correctly

	1800ft⋅lb
	900ft⋅lb
	0ft⋅lb
	3600 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 6 will multiply an input effort of 600 ft⋅lb by 6 to produce an output effort of 3600 ft⋅lb.

Which of the following is not a type of bridge?

74% Answer Correctly

	block
	truss
	arch
	cable

Solution

The six basic bridge forms are beam, truss, arch, cantilever, cable, and suspension.

A wedge is most similar to what other type of simple machine?

70% Answer Correctly

	third-class lever
	first-class lever
	inclined plane
	second-class lever

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.

If the handles of a wheelbarrow are 3 ft. from the wheel axle, what force must you exert to lift the handles if it's carrying a 270 lb. load concentrated at a point 0.5 ft. from the axle?

56% Answer Correctly

	90 lbs
	45 lbs
	810 lbs
	0.83 lbs

Solution

This problem describes a second-class lever and, for a second class lever, 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 3 ft. = 270 lbs x 0.5 ft
F_e = 135 ft-lb. / 3 ft
F_e= 45 lbs

Which class of lever is used to increase force on an object in the same direction as the force is applied?

53% Answer Correctly

	all of these
	first
	third
	second

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.