ASVAB Mechanical Comprehension Practice Test 717339 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.90
Score	0%	58%

Review

A wedge is most similar to what other type of simple machine?

70% Answer Correctly

	inclined plane
	third-class lever
	first-class lever
	second-class lever

Solution

The wedge is a moving inclined plane that is used to lift, hold, or break apart an object. A wedge converts force applied to its blunt end into force perpendicular to its inclined surface. In contrast to a stationary plane where force is applied to the object being moved, with a wedge the object is stationary and the force is being applied to the plane. Examples of a wedge include knives and chisels.

A truck is using a rope to pull a car. Tension in the rope is greatest in which of the following places?

50% Answer Correctly

	near the car
	tension is equal in all parts of the rope
	near the truck
	in the middle

Solution

Tension is a force that stretches or elongates something. When a cable or rope is used to pull an object, for example, it stretches internally as it accepts the weight that it's moving. Although tension is often treated as applying equally to all parts of a material, it's greater at the places where the material is under the most stress.

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

54% Answer Correctly

	its direction
	its speed
	its weight
	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.

4 A = 8 ft., the green box weighs 40 lbs., and the blue box weighs 80 lbs. What does distance B need to be for this lever to balance?

64% Answer Correctly

	4 ft.
	5 ft.
	320 ft.
	0 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:

40 lbs. x 8 ft. = 80 lbs. x d_B

d_B = \( \frac{40 \times 8 ft⋅lb}{80 lbs.} \) = \( \frac{320 ft⋅lb}{80 lbs.} \) = 4 ft.

Which of the following represents how much two materials resist sliding across each other?

53% Answer Correctly

	normal friction
	kinetic friction
	static friction
	coefficient of friction

Solution

Coefficient of friction (μ) represents how much two materials resist sliding across each other. Smooth surfaces like ice have low coefficients of friction while rough surfaces like concrete have high μ.