ASVAB Mechanical Comprehension Practice Test 634880 Results

Your Results Global Average
Questions 5 5
Correct 0 2.78
Score 0% 56%

Review

1 A = 9 ft., the green box weighs 25 lbs., and the blue box weighs 70 lbs. What does distance B need to be for this lever to balance?
65% Answer Correctly
1.61 ft.
9.64 ft.
0.8 ft.
3.21 ft.
Solution
In order for this lever to balance, the torque acting on side A must equal the torque acting on side B. Torque is weight x distance from the fulcrum which means that the following must be true for the lever to balance:

fAdA = fBdB

For this problem, the equation becomes:

25 lbs. x 9 ft. = 70 lbs. x dB

dB = \( \frac{25 \times 9 ft⋅lb}{70 lbs.} \) = \( \frac{225 ft⋅lb}{70 lbs.} \) = 3.21 ft.

2

A wedge converts force applied to its blunt end into force __________ its inclined surface.

57% Answer Correctly

parallel to

along

opposite to

perpendicular to
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

Which class of lever offers no mechanical advantage?

45% Answer Correctly

none of these, all levers offer mechanical advantage

first

second

third
Solution

A third-class lever is used to increase distance traveled by an object in the same direction as the force applied. The fulcrum is at one end of the lever, the object at the other, and the force is applied between them. This lever does not impart a mechanical advantage as the effort force must be greater than the load but does impart extra speed to the load. Examples of third-class levers are shovels and tweezers.

4

A screw is most like which of the following other simple machines?

50% Answer Correctly

block and tackle

wheel and axle

inclined plane

first-class lever
Solution

A screw is an inclined plane wrapped in ridges (threads) around a cylinder. The distance between these ridges defines the pitch of the screw and this distance is how far the screw advances when it is turned once. The mechanical advantage of a screw is its circumference divided by the pitch.

5

Gear ratio indicates which of the following about two connected gears?

59% Answer Correctly

power conversion

work done

mechanical advantage

efficiency
Solution

The mechanical advantage (amount of change in speed or torque) of connected gears is proportional to the number of teeth each gear has. Called gear ratio, it's the ratio of the number of teeth on the larger gear to the number of teeth on the smaller gear.  For example, a gear with 12 teeth connected to a gear with 9 teeth would have a gear ratio of 4:3.