ASVAB Mechanical Comprehension Practice Test 382659 Results

Your Results Global Average
Questions 5 5
Correct 0 2.76
Score 0% 55%

Review

1

What defines the mechanical advantage of a first class lever?

65% Answer Correctly

output distance

output force 

position of the fulcrum

input force
Solution

A first-class lever is used to increase force or distance while changing the direction of the force. The lever pivots on a fulcrum and, when a force is applied to the lever at one side of the fulcrum, the other end moves in the opposite direction. The position of the fulcrum also defines the mechanical advantage of the lever. If the fulcrum is closer to the force being applied, the load can be moved a greater distance at the expense of requiring a greater input force. If the fulcrum is closer to the load, less force is required but the force must be applied over a longer distance. An example of a first-class lever is a seesaw / teeter-totter.

2

Depending on where you apply effort and resistance, the wheel and axle can multiply:

45% Answer Correctly

speed or power

power or distance

force or distance

force or speed
Solution

If you apply the resistance to the axle and the effort to the wheel, the wheel and axle will multiply force and if you apply the resistance to the wheel and the effort to the axle, it will multiply speed.

3 If the handles of a wheelbarrow are 2.0 ft. from the wheel axle and the load is concentrated at a point 1.0 ft. from the axle, how many pounds of load will a 210 lbs. force lift?
47% Answer Correctly
0
210
105
420
Solution
This problem describes a second-class lever and, for a second class lever, the effort force multiplied by the effort distance equals the resistance force multipied by the resistance distance: Fede = Frdr. In this problem we're looking for resistance force:
\( F_r = \frac{F_e d_e}{d_r} \)
\( F_r = \frac{210 \times 2.0}{1.0} \)
\( F_r = \frac{420.0}{1.0} \)
\( F_r = 420 \)
4 A = 4 ft., the green box weighs 10 lbs., and the blue box weighs 20 lbs. What does distance B need to be for this lever to balance?
65% Answer Correctly
0.5 ft.
0.67 ft.
2 ft.
40 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:

10 lbs. x 4 ft. = 20 lbs. x dB

dB = \( \frac{10 \times 4 ft⋅lb}{20 lbs.} \) = \( \frac{40 ft⋅lb}{20 lbs.} \) = 2 ft.

5

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

54% Answer Correctly

its direction

its weight

its mass

its speed
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.