ASVAB Mechanical Comprehension Practice Test 419321 Results

Your Results Global Average
Questions 5 5
Correct 0 3.03
Score 0% 61%

Review

1 50 lbs. of effort is used by a machine to lift a 100 lbs. box. What is the mechanical advantage of the machine?
84% Answer Correctly
2.2
1.8
2
3
Solution

Mechanical advantage is resistance force divided by effort force:

MA = \( \frac{F_r}{F_e} \) = \( \frac{100 lbs.}{50 lbs.} \) = 2

2

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

57% Answer Correctly

air

carbon

oil

water
Solution

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

3

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

48% Answer Correctly

counter force

normal force

mass

friction
Solution

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

4 If the green box weighs 10 lbs. and is 9 ft. from the fulcrum, how far from the fulcrum would a 15 lbs. force need to be applied to balance the lever?
58% Answer Correctly
6 ft.
18 ft.
12 ft.
3 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 = \( \frac{R_ad_a}{R_b} \) = \( \frac{10 lbs. \times 9 ft.}{15 lbs.} \) = \( \frac{90 ft⋅lb}{15 lbs.} \) = 6 ft.

5

Which of the following will increase the mechanical advantage of this inclined plane?

59% Answer Correctly

shorten the ramp

lengthen the ramp

increase the force acting at the blue arrow

lower the force acting at the blue arrow
Solution

The mechanical advantage (MA) of an inclined plane is the effort distance divided by the resistance distance. In order to increase mechanical advantage, this ratio must increase which means making the effort distance longer and this can be accomplished by lengthening the length of the ramp.