ASVAB Mechanical Comprehension Practice Test 949972 Results

Your Results Global Average
Questions 5 5
Correct 0 2.80
Score 0% 56%

Review

1

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

pressure, density

density, volume

volume, mass
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".

2 If the green box weighs 40 lbs. and is 5 ft. from the fulcrum, how far from the fulcrum would a 20 lbs. weight need to be placed to balance the lever?
61% Answer Correctly
2.5 ft.
10 ft.
40 ft.
5 ft.
Solution

To balance this lever the torques on each side of the fulcrum must be equal. Torque is weight x distance from the fulcrum so the equation for equilibrium is:

Rada = Rbdb

where a represents the left side of the fulcrum and b the right, R is resistance (weight) and d is the distance from the fulcrum.

Solving for db, our missing value, and plugging in our variables yields:

db = \( \frac{R_ad_a}{R_b} \) = \( \frac{40 lbs. \times 5 ft.}{20 lbs.} \) = \( \frac{200 ft⋅lb}{20 lbs.} \) = 10 ft.

3 If the green box weighs 10 lbs. and is 9 ft. from the fulcrum, how far from the fulcrum would a 65 lbs. force need to be applied to balance the lever?
58% Answer Correctly
0 ft.
1.38 ft.
0.69 ft.
4.15 ft.
Solution

To balance this lever the torques at the green box and the blue arrow must be equal. Torque is weight x distance from the fulcrum so the equation for equilibrium is:

Rada = Rbdb

where a represents the green box and b the blue arrow, R is resistance (weight/force) and d is the distance from the fulcrum.

Solving for db, our missing value, and plugging in our variables yields:

db = \( \frac{R_ad_a}{R_b} \) = \( \frac{10 lbs. \times 9 ft.}{65 lbs.} \) = \( \frac{90 ft⋅lb}{65 lbs.} \) = 1.38 ft.

4

Lisa lifts a 25 pound box from the floor onto a loading dock 4 ft. off the ground. Sam slides the same box along a ramp to move it up another 4 ft. onto a flatbed truck. Who has done more work?

50% Answer Correctly

They have done an equal amount of work

Lisa

Sam

Neither have done any work
Solution

Work is force multiplied by distance. Because both Connie and Sam moved the same weight the same distance they have done an equal amount of work. Sam employed the mechnacial advantage of an inclined plane so he exerted less effort to do the work but the amount of work done was still the same.

5

Which of the following represents the force a surface exerts when an object presses against it?

48% Answer Correctly

friction

mass

counter force

normal force
Solution

Normal force (FN) represents the force a surface exerts when an object presses against it.