ASVAB Mechanical Comprehension Practice Test 136979 Results

Your Results Global Average
Questions 5 5
Correct 0 3.17
Score 0% 63%

Review

1

What type of load is sudden and for a relatively short duration?

69% Answer Correctly

dynamic load

impact load

concentrated load

non-uniformly distributed load
Solution

A concentrated load acts on a relatively small area of a structure, a static uniformly distributed load doesn't create specific stress points or vary with time, a dynamic load varies with time or affects a structure that experiences a high degree of movement, an impact load is sudden and for a relatively short duration and a non-uniformly distributed load creates different stresses at different locations on a structure.

2 If the green box weighs 5 lbs. and is 7 ft. from the fulcrum, how far from the fulcrum would a 55 lbs. weight need to be placed to balance the lever?
61% Answer Correctly
2.55 ft.
0.21 ft.
0.16 ft.
0.64 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 = \( \frac{R_ad_a}{R_b} \) = \( \frac{5 lbs. \times 7 ft.}{55 lbs.} \) = \( \frac{35 ft⋅lb}{55 lbs.} \) = 0.64 ft.

3

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

48% Answer Correctly

mass

normal force

friction

counter force
Solution

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

4 What is the efficiency of a machine has work input of 85 ft⋅lb and work output of 46 ft⋅lb?
67% Answer Correctly
55%
220%
110%
27%
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:
\( Efficiency = \frac{Work_{out}}{Work_{in}} \times 100 \) \( = \frac{46 ft⋅lb}{85 ft⋅lb} \times 100 \) \( = 55% \) %
5

Which of the following is not a type of bridge?

74% Answer Correctly

arch

cable

truss

block
Solution

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