ASVAB Mechanical Comprehension Practice Test 522834 Results

Your Results Global Average
Questions 5 5
Correct 0 3.72
Score 0% 74%

Review

1

A ramp is an example of which kind of simple machine?

84% Answer Correctly

inclined plane

first-class lever

none of these

wedge


Solution

An inclined plane is a simple machine that reduces the force needed to raise an object to a certain height. Work equals force x distance and, by increasing the distance that the object travels, an inclined plane reduces the force necessary to raise it to a particular height. In this case, the mechanical advantage is to make the task easier. An example of an inclined plane is a ramp.


2

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

61% Answer Correctly

low density

chemically stable

low corrosive action

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.


3 If the green box weighs 35 lbs. and is 5 ft. from the fulcrum, how much weight would need to be placed at the blue arrow to balance the lever if the arrow's distance from the fulcrum is 8 ft.?
63% Answer Correctly
10.94 lbs.
21.88 lbs.
65.63 lbs.
87.5 lbs.

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 Rb, our missing value, and plugging in our variables yields:

Rb = \( \frac{R_ad_a}{d_b} \) = \( \frac{35 lbs. \times 5 ft.}{8 ft.} \) = \( \frac{175 ft⋅lb}{8 ft.} \) = 21.88 lbs.


4 What's the mechanical advantage of a wedge that's 2 inches wide and 4 inches long?
83% Answer Correctly
2.2
1
2
3.5

Solution

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

MA = \( \frac{l}{t} \) = \( \frac{4 in.}{2 in.} \) = 2


5

When all forces acting on a system cancel each other out, this is called:

80% Answer Correctly

equilibrium

rest

stasis

potential energy


Solution

When a system is stable or balanced (equilibrium) all forces acting on the system cancel each other out. In the case of torque, equilibrium means that the sum of the anticlockwise moments about a center of rotation equal the sum of the clockwise moments.