ASVAB Mechanical Comprehension Practice Test 67174 Results

Your Results Global Average
Questions 5 5
Correct 0 3.45
Score 0% 69%

Review

1

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

70% Answer Correctly

impact load

dynamic load

non-uniformly distributed load

concentrated 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

A wedge is most similar to what other type of simple machine?

70% Answer Correctly

inclined plane

first-class lever

third-class lever

second-class lever
Solution

The wedge is a moving inclined plane that is used to lift, hold, or break apart an object. A wedge converts force applied to its blunt end into force perpendicular to its inclined surface. In contrast to a stationary plane where force is applied to the object being moved, with a wedge the object is stationary and the force is being applied to the plane. Examples of a wedge include knives and chisels.

3

The force required to initally get an object moving is __________ the force required to keep it moving. 

76% Answer Correctly

opposite

lower than

higher than

the same as
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).

4 What's the mechanical advantage of a wedge that's 5 inches wide and 35 inches long?
83% Answer Correctly
7.7
6
7
8.5
Solution

The mechanical advantage (MA) of a wedge is its length divided by its thickness:

MA = \( \frac{l}{t} \) = \( \frac{35 in.}{5 in.} \) = 7

5 If A = 12 ft., B = 3 ft., C = 10 ft., the green box weighs 25 lbs. and the blue box weighs 35 lbs., what does the orange box have to weigh for this lever to balance?
44% Answer Correctly
78 lbs.
300 lbs.
19.5 lbs.
6.5 lbs.
Solution
In order for this lever to balance, the torque acting on each side of the fulrum must be equal. So, the torque produced by A must equal the torque produced by B and C. Torque is weight x distance from the fulcrum which means that the following must be true for the lever to balance:

fAdA = fBdB + fCdC

For this problem, this equation becomes:

25 lbs. x 12 ft. = 35 lbs. x 3 ft. + fC x 10 ft.

300 ft. lbs. = 105 ft. lbs. + fC x 10 ft.

fC = \( \frac{300 ft. lbs. - 105 ft. lbs.}{10 ft.} \) = \( \frac{195 ft. lbs.}{10 ft.} \) = 19.5 lbs.