ASVAB Mechanical Comprehension Practice Test 516836 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.57
Score	0%	51%

Review

A box is resting on a smooth floor. Static friction is present:

59% Answer Correctly

	only if normal force is present
	if the coefficient of friction is greater than one
	at all times
	when an attempt is made to move the box

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).

Coplanar forces:

62% Answer Correctly

	have opposite dimensions
	act in a common plane
	pass through a common point
	act along the same line of action

Solution

Collinear forces act along the same line of action, concurrent forces pass through a common point and coplanar forces act in a common plane.

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

59% Answer Correctly

	efficiency
	power conversion
	mechanical advantage
	work done

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.

The advantage of using a third-class lever is that it increases:

37% Answer Correctly

	the speed of the load
	the mechanical advantage of the lever
	the force applied to the load
	the distance traveled by the load

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.

5 If the radius of the axle is 5 and the radius of the wheel is 10, what is the mechanical advantage of this wheel and axle configuration?

36% Answer Correctly

	2
	0
	1
	10

Solution

The mechanical advantage of a wheel and axle lies in the difference in radius between the inner (axle) wheel and the outer wheel. But, this mechanical advantage is only realized when the input effort and load are applied to different wheels. Applying both input effort and load to the same wheel results in a mechanical advantage of 1.