ASVAB Mechanical Comprehension Practice Test 310091 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.14
Score	0%	63%

Review

1 What is the efficiency of a machine has work input of 160 ft⋅lb and work output of 144 ft⋅lb?

67% Answer Correctly

	90%
	180%
	1%
	45%

Solution

Due to friction, a machine will never be able to utilize 100% of its work input. A certain percentage of that input will be lost in overcoming friction within the machine. Effeciency is a measure of how much of a machine's work input can be turned into useful work output and is calculated by dividing work output by work input and multiplying the result by 100:
\( Efficiency = \frac{Work_{out}}{Work_{in}} \times 100 \) \( = \frac{144 ft⋅lb}{160 ft⋅lb} \times 100 \) \( = 90% \) %

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

57% Answer Correctly

	along
	opposite to
	parallel to
	perpendicular to

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.

What's the first gear in a gear train called?

57% Answer Correctly

	driven gear
	input gear
	driver gear
	idler gear

Solution

A gear train is two or more gears linked together. Gear trains are designed to increase or reduce the speed or torque outpout of a rotating system or change the direction of its output. The first gear in the chain is called the driver and the last gear in the chain the driven gear with the gears between them called idler gears.

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

53% Answer Correctly

	third
	second
	first
	all of these

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.

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

81% Answer Correctly

	heat
	work
	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.