ASVAB Mechanical Comprehension Practice Test 491553 Results

Your Results Global Average
Questions 5 5
Correct 0 2.74
Score 0% 55%

Review

1 If the green box weighs 10 lbs. and 60 lbs. of force is applied 3 ft. from the fulcrum at the blue arrow, how far from the fulcrum would the green box need to be placed to balance the lever?
55% Answer Correctly
18 ft.
9 ft.
72 ft.
36 ft.

Solution

To balance this lever the torques at the green box and the blue arrow must be equal. Torque is weight x distance from the fulcrum so the equation for equilibrium is:

Rada = Rbdb

where a represents the green box and b the blue arrow, R is resistance (weight/force) and d is the distance from the fulcrum.

Solving for da, our missing value, and plugging in our variables yields:

da = \( \frac{R_bd_b}{R_a} \) = \( \frac{60 lbs. \times 3 ft.}{10 lbs.} \) = \( \frac{180 ft⋅lb}{10 lbs.} \) = 18 ft.


2

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

57% Answer Correctly

parallel to

opposite to

perpendicular to

along


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 measure of how much of the power put into a machine is turned into movement or force is called:

56% Answer Correctly

mechanical advantage

power

force multiplication

efficiency


Solution

The efficiency of a machine describes how much of the power put into the machine is turned into movement or force. A 100% efficient machine would turn all of the input power into output movement or force. However, no machine is 100% efficient due to friction, heat, wear and other imperfections that consume input power without delivering any output.


4

Depending on where you apply effort and resistance, the wheel and axle can multiply:

45% Answer Correctly

speed or power

power or distance

force or distance

force or speed


Solution

If you apply the resistance to the axle and the effort to the wheel, the wheel and axle will multiply force and if you apply the resistance to the wheel and the effort to the axle, it will multiply speed.


5

Which of the following is not a characteristic of a ceramic?

61% Answer Correctly

low density

low corrosive action

chemically stable

high melting point


Solution

Ceramics are mixtures of metallic and nonmetallic elements that withstand exteme thermal, chemical, and pressure environments. They have a high melting point, low corrosive action, and are chemically stable. Examples include rock, sand, clay, glass, brick, and porcelain.