ASVAB Mechanical Comprehension Practice Test 116038 Results

Your Results Global Average
Questions 5 5
Correct 0 2.66
Score 0% 53%

Review

1

Which class of lever offers no mechanical advantage?

45% Answer Correctly

none of these, all levers offer mechanical advantage

third

first

second
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.

2

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

54% Answer Correctly

its direction

its weight

its speed

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.

3 A = 8 ft., the green box weighs 5 lbs., and the blue box weighs 45 lbs. What does distance B need to be for this lever to balance?
65% Answer Correctly
3.56 ft.
0.22 ft.
0 ft.
0.89 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:

fAdA = fBdB

For this problem, the equation becomes:

5 lbs. x 8 ft. = 45 lbs. x dB

dB = \( \frac{5 \times 8 ft⋅lb}{45 lbs.} \) = \( \frac{40 ft⋅lb}{45 lbs.} \) = 0.89 ft.

4

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

37% Answer Correctly

the distance traveled by the load

the force applied to the load

the mechanical advantage of the lever

the speed of 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

Normal force is generally equal to the __________ of an object.

62% Answer Correctly

weight

density

mass

coefficient of friction
Solution

Normal force arises on a flat horizontal surface in response to an object's weight pressing it down. Consequently, normal force is generally equal to the object's weight.