ASVAB Mechanical Comprehension Practice Test 669036 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.11
Score	0%	62%

Review

Coplanar forces:

61% Answer Correctly

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

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.

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

76% Answer Correctly

	the same as
	lower than
	opposite
	higher 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 fixed pulley is useful for which of the following?

53% Answer Correctly

	changing the direction of the output force
	multiplying the input distance
	changing the direction of the input force
	multiplying the input force

Solution

A fixed pulley is used to change the direction of a force and does not multiply the force applied. As such, it has a mechanical advantage of one. The benefit of a fixed pulley is that it can allow the force to be applied at a more convenient angle, for example, pulling downward or horizontally to lift an object instead of upward.

4 A = 4 ft., the green box weighs 30 lbs., and the blue box weighs 75 lbs. What does distance B need to be for this lever to balance?

65% Answer Correctly

	300 ft.
	6.4 ft.
	18 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:

30 lbs. x 4 ft. = 75 lbs. x d_B

d_B = \( \frac{30 \times 4 ft⋅lb}{75 lbs.} \) = \( \frac{120 ft⋅lb}{75 lbs.} \) = 1.6 ft.

Which of these will have the most impact on the kinetic energy of an object?

54% Answer Correctly

	its weight
	its speed
	its direction
	its mass

Solution

Kinetic energy is the energy of movement and is a function of the mass of an object and its speed: \(KE = {1 \over 2}mv^2\) where m is mass in kilograms, v is speed in meters per second, and KE is in joules. The most impactful quantity to kinetic energy is velocity as an increase in mass increases KE linearly while an increase in speed increases KE exponentially.