ASVAB Mechanical Comprehension Practice Test 376839 Results

Your Results Global Average
Questions 5 5
Correct 0 3.00
Score 0% 60%

Review

1 If the green box weighs 15 lbs. and 15 lbs. of force is applied 9 ft. from the fulcrum at the blue arrow, how far from the fulcrum would the green box need to be placed to balance the lever?
55% Answer Correctly
18 ft.
9 ft.
1 ft.
135 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 da, our missing value, and plugging in our variables yields:

da = \( \frac{R_bd_b}{R_a} \) = \( \frac{15 lbs. \times 9 ft.}{15 lbs.} \) = \( \frac{135 ft⋅lb}{15 lbs.} \) = 9 ft.

2

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

volume, mass

pressure, density

pressure, volume

density, volume
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".

3

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

48% Answer Correctly

friction

counter force

mass

normal force
Solution

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

4 How much resistance could a 220 lb. effort force lift using a block and tackle pulley that has 10 ropes supporting the resistance?
81% Answer Correctly
1980 lbs.
1100 lbs.
2200 lbs.
3300 lbs.
Solution

The mechanical advantage (MA) of a block and tackle pulley is equal to the number of times the effort force changes direction. An easy way to count how many times the effort force changes direction is to count the number of ropes that support the resistance which, in this problem, is 10. With a MA of 10, a 220 lbs. effort force could lift 220 lbs. x 10 = 2200 lbs. resistance.

5

Concurrent forces:

55% Answer Correctly

pass through a common point

act in a common dimension

act in a common plane

act along the same line of action
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.