ASVAB Mechanical Comprehension Practice Test 611440 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.88
Score	0%	58%

Review

1 How much work can a 3 hp engine do in 3 seconds?

52% Answer Correctly

	4950 ft⋅lb
	6 ft⋅lb
	12 ft⋅lb
	0 ft⋅lb

Solution

Horsepower (hp) is a common measure of power output for complex machines. By definition, a 1 hp machine does 550 ft⋅lb of work in 1 second: 1 hp = 550 ft⋅lb/s. Substituting the variables for this problem gives us:
\( W = 3 hp \times 550 \frac{ft⋅lb}{s} \times 3s = 4950 ft⋅lb \)

The mechanical advantage of a wheel and axle is equal to the:

61% Answer Correctly

	ratio of the diameters of the wheels
	difference in the lengths of the axles
	difference in the diameters of the wheels
	length of the axle

Solution

A wheel and axle uses two different diameter wheels mounted to a connecting axle. Force is applied to the larger wheel and large movements of this wheel result in small movements in the smaller wheel. Because a larger movement distance is being translated to a smaller distance, force is increased with a mechanical advantage equal to the ratio of the diameters of the wheels. An example of a wheel and axle is the steering wheel of a car.

The principle of moments defines equilibrium in terms of:

53% Answer Correctly

	speed
	torque
	energy
	power

Solution

According to the principle of moments, you can maintain equilibrium if the moments (forces) tending to clockwise rotation are equal to the moments tending to counterclockwise rotation. Another name for these moments of force is torque.

Which of the following is not true of a first-class lever?

51% Answer Correctly

	changes the direction of force
	increases force
	decreases distance
	increases distance

Solution

A first-class lever is used to increase force or distance while changing the direction of the force. The lever pivots on a fulcrum and, when a force is applied to the lever at one side of the fulcrum, the other end moves in the opposite direction. The position of the fulcrum also defines the mechanical advantage of the lever. If the fulcrum is closer to the force being applied, the load can be moved a greater distance at the expense of requiring a greater input force. If the fulcrum is closer to the load, less force is required but the force must be applied over a longer distance. An example of a first-class lever is a seesaw / teeter-totter.

Two or more pulleys used together are called:

71% Answer Correctly

	block and tackle
	third-class lever
	wheel and axle
	gears

Solution

Two or more pulleys used together constitute a block and tackle which, unlike a fixed pulley, does impart mechanical advantage as a function of the number of pulleys that make up the arrangement. So, for example, a block and tackle with three pulleys would have a mechanical advantage of three.