ASVAB Mechanical Comprehension Practice Test 509653 Results

Your Results Global Average
Questions 5 5
Correct 0 3.32
Score 0% 66%

Review

1 If the green box weighs 10 lbs. and is 7 ft. from the fulcrum, how far from the fulcrum would a 30 lbs. weight need to be placed to balance the lever?
61% Answer Correctly
0 ft.
2.33 ft.
0.78 ft.
1 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 = \( \frac{R_ad_a}{R_b} \) = \( \frac{10 lbs. \times 7 ft.}{30 lbs.} \) = \( \frac{70 ft⋅lb}{30 lbs.} \) = 2.33 ft.

2

Which of the following is not a type of structural load?

49% Answer Correctly

dead load

wind load

live load

occupancy load
Solution

Dead load is the weight of the building and materials, live load is additional weight due to occupancy or use, snow load is the weight of accumulated snow on a structure and wind load is the force of wind pressures against structure surfaces.

3 What is the efficiency of a machine has work input of 75 ft⋅lb and work output of 56 ft⋅lb?
67% Answer Correctly
300%
0%
75%
18%
Solution
Due to friction, a machine will never be able to utilize 100% of its work input. A certain percentage of that input will be lost in overcoming friction within the machine. Effeciency is a measure of how much of a machine's work input can be turned into useful work output and is calculated by dividing work output by work input and multiplying the result by 100:
\( Efficiency = \frac{Work_{out}}{Work_{in}} \times 100 \) \( = \frac{56 ft⋅lb}{75 ft⋅lb} \times 100 \) \( = 75% \) %
4

Which of these is the formula for force?

76% Answer Correctly

F = ma

F = m/a

F = am2

F = a/m
Solution

Newton's Second Law of Motion states that "The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object." This Law describes the linear relationship between mass and acceleration when it comes to force and leads to the formula F = ma or force equals mass multiplied by rate of acceleration.

5

Which of the following is not a type of bridge?

74% Answer Correctly

cable

block

arch

truss
Solution

The six basic bridge forms are beam, truss, arch, cantilever, cable, and suspension.