ASVAB Mechanical Comprehension Practice Test 427890 Results

Your Results Global Average
Questions 5 5
Correct 0 3.09
Score 0% 62%

Review

1 If A = 12 ft., B = 3 ft., C = 9 ft., the green box weighs 35 lbs. and the blue box weighs 40 lbs., what does the orange box have to weigh for this lever to balance?
44% Answer Correctly
2 lbs.
33.33 lbs.
11 lbs.
16.67 lbs.
Solution
In order for this lever to balance, the torque acting on each side of the fulrum must be equal. So, the torque produced by A must equal the torque produced by B and C. Torque is weight x distance from the fulcrum which means that the following must be true for the lever to balance:

fAdA = fBdB + fCdC

For this problem, this equation becomes:

35 lbs. x 12 ft. = 40 lbs. x 3 ft. + fC x 9 ft.

420 ft. lbs. = 120 ft. lbs. + fC x 9 ft.

fC = \( \frac{420 ft. lbs. - 120 ft. lbs.}{9 ft.} \) = \( \frac{300 ft. lbs.}{9 ft.} \) = 33.33 lbs.

2

Specific gravity is a comparison of the density of an object with the density of:

57% Answer Correctly

oil

carbon

water

air
Solution

Specific gravity is the ratio of the density of equal volumes of a substance and water and is measured by a hyrdometer.

3 If you lift a 33 lbs. rock 26 ft. from the ground, how much work have you done?
70% Answer Correctly
59 ft⋅lb
1716 ft⋅lb
0 ft⋅lb
858 ft⋅lb
Solution
Work is force times distance. In this case, the force is the weight of the rock so:
\( W = F \times d \)
\( W = 33 \times 26 \)
\( W = 858 \)
4

The mass of an object correlates to the size of the object but ultimately depends on:

66% Answer Correctly

gravity

the object's potential energy

the object's density

the object's weight
Solution

Mass is a measure of the amount of matter in an object.  In general, larger objects have larger mass than smaller objects but mass ultimately depends on how compact (dense) a substance is.

5

A fixed pulley has a mechanical advantage of:

68% Answer Correctly

2

0

-1

1
Solution

A fixed pulley is used to change the direction of a force and does not multiply the force applied. As such, it has a mechanical advantage of one. The benefit of a fixed pulley is that it can allow the force to be applied at a more convenient angle, for example, pulling downward or horizontally to lift an object instead of upward.