ASVAB Mechanical Comprehension Practice Test 14298 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.75
Score	0%	55%

Review

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

50% Answer Correctly

	dead load
	occupancy load
	live load
	wind 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.

2 If the force applied at the blue arrow over 9 ft. moves the green box 1.5 ft., what is the mechanical advantage of this lever?

56% Answer Correctly

	5.4
	6
	3
	18

Solution

Mechanical advantage (MA) can be calculated knowing only the distance the effort (blue arrow) moves and the distance the resistance (green box) moves. The equation is:

MA = \( \frac{E_d}{R_d} \)

where E_d is the effort distance and R_d is the resistance distance. For this problem, the equation becomes:

MA = \( \frac{9 ft.}{1.5 ft.} \) = 6

You might be wondering how having an effort distance of 6 times the resistance distance is an advantage. Remember the principle of moments. For a lever in equilibrium the effort torque equals the resistance torque. Because torque is force x distance, if the effort distance is 6 times the resistance distance, the effort force must be \( \frac{1}{6} \) the resistance force. You're trading moving 6 times the distance for only having to use \( \frac{1}{6} \) the force.

For any given surface, the coefficient of static friction is ___________ the coefficient of kinetic friction.

54% Answer Correctly

	higher than
	equal to
	opposite
	lower than

Solution

For any given surface, the coefficient of static friction is higher than the coefficient of kinetic friction. More force is required to initally get an object moving than is required to keep it moving. Additionally, static friction only arises in response to an attempt to move an object (overcome the normal force between it and the surface).

A shovel is an example of which class of lever?

56% Answer Correctly

	first
	a shovel is not a lever
	second
	third

Solution

A third-class lever is used to increase distance traveled by an object in the same direction as the force applied. The fulcrum is at one end of the lever, the object at the other, and the force is applied between them. This lever does not impart a mechanical advantage as the effort force must be greater than the load but does impart extra speed to the load. Examples of third-class levers are shovels and tweezers.

Gear ratio indicates which of the following about two connected gears?

59% Answer Correctly

	power conversion
	mechanical advantage
	work done
	efficiency

Solution

The mechanical advantage (amount of change in speed or torque) of connected gears is proportional to the number of teeth each gear has. Called gear ratio, it's the ratio of the number of teeth on the larger gear to the number of teeth on the smaller gear. For example, a gear with 12 teeth connected to a gear with 9 teeth would have a gear ratio of 4:3.