ASVAB Mechanical Comprehension Practice Test 804980 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.19
Score	0%	64%

Review

The force required to initally get an object moving is __________ the force required to keep it moving.

76% Answer Correctly

	opposite
	lower than
	higher than
	the same as

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
	pass through a common point
	act in a common plane
	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.

According to Boyle's law, for a fixed amount of gas kept at a fixed temperature, which of the following are inversely proportional?

63% Answer Correctly

	pressure, volume
	volume, mass
	pressure, density
	density, volume

Solution

Boyle's law states that "for a fixed amount of an ideal gas kept at a fixed temperature, pressure and volume are inversely proportional".

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

53% Answer Correctly

	first
	third
	second
	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.

5 A = 4 ft., the green box weighs 5 lbs., and the blue box weighs 50 lbs. What does distance B need to be for this lever to balance?

65% Answer Correctly

	0.2 ft.
	0.13 ft.
	0.4 ft.
	1.6 ft.

Solution

In order for this lever to balance, the torque acting on side A must equal the torque acting on side B. Torque is weight x distance from the fulcrum which means that the following must be true for the lever to balance:

f_Ad_A = f_Bd_B

For this problem, the equation becomes:

5 lbs. x 4 ft. = 50 lbs. x d_B

d_B = \( \frac{5 \times 4 ft⋅lb}{50 lbs.} \) = \( \frac{20 ft⋅lb}{50 lbs.} \) = 0.4 ft.