ASVAB Mechanical Comprehension Practice Test 681994 Results

Your Results Global Average
Questions 5 5
Correct 0 2.87
Score 0% 57%

Review

1

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

59% Answer Correctly

lengthen the ramp

increase the force acting at the blue arrow

shorten the ramp

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.

2 What is the efficiency of a machine has work input of 95 ft⋅lb and work output of 61 ft⋅lb?
67% Answer Correctly
65%
0%
260%
16%
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:
\( Efficiency = \frac{Work_{out}}{Work_{in}} \times 100 \) \( = \frac{61 ft⋅lb}{95 ft⋅lb} \times 100 \) \( = 65% \) %
3

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

49% Answer Correctly

live load

wind load

occupancy load

dead 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.

4

A box is resting on a smooth floor. Static friction is present:

60% Answer Correctly

at all times

only if normal force is present

if the coefficient of friction is greater than one

when an attempt is made to move the box
Solution

For any given surface, the coefficient of static friction is higher than the coefficient of kinetic friction. More force is required to initally get an object moving than is required to keep it moving. Additionally, static friction only arises in response to an attempt to move an object (overcome the normal force between it and the surface).

5 A 250 lb. barrel is rolled up a 16 ft. ramp to a platform that's 2 ft. tall. What effort is required to move the barrel?
53% Answer Correctly
46.9 lbs.
31.3 lbs.
32.8 lbs.
34.3 lbs.
Solution

This problem describes an inclined plane and, for an inclined plane, the effort force multiplied by the effort distance equals the resistance force multipied by the resistance distance:

Fede = Frdr

Plugging in the variables from this problem yields:

Fe x 16 ft. = 250 lbs. x 2 ft.
Fe = \( \frac{500 ft⋅lb}{16 ft.} \) = 31.3 lbs.