ASVAB Mechanical Comprehension Practice Test 448908 Results

Your Results Global Average
Questions 5 5
Correct 0 3.10
Score 0% 62%

Review

1 If the green box weighs 55 lbs. and is 5 ft. from the fulcrum, how far from the fulcrum would a 45 lbs. weight need to be placed to balance the lever?
61% Answer Correctly
275 ft.
12.22 ft.
6.11 ft.
3.06 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 = \( \frac{R_ad_a}{R_b} \) = \( \frac{55 lbs. \times 5 ft.}{45 lbs.} \) = \( \frac{275 ft⋅lb}{45 lbs.} \) = 6.11 ft.

2

Which of the following represents how much two materials resist sliding across each other?

53% Answer Correctly

static friction

normal friction

kinetic friction

coefficient of friction
Solution

Coefficient of friction (μ) represents how much two materials resist sliding across each other.  Smooth surfaces like ice have low coefficients of friction while rough surfaces like concrete have high μ.

3

An object's resistance to changes in direction is known as:

82% Answer Correctly

kinetic energy

weight

inertia

mass
Solution

The more mass a substance has the more force is required to move it or to change its direction. This resistance to changes in direction is known as inertia.

4

Normal force is generally equal to the __________ of an object.

61% Answer Correctly

density

mass

weight

coefficient of friction
Solution

Normal force arises on a flat horizontal surface in response to an object's weight pressing it down. Consequently, normal force is generally equal to the object's weight.

5

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

48% Answer Correctly

normal force

friction

counter force

mass
Solution

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