ASVAB Mechanical Comprehension Practice Test 835568 Results

Your Results Global Average
Questions 5 5
Correct 0 3.09
Score 0% 62%

Review

1

Which of the following is not a type of simple machine?

58% Answer Correctly

pulley

lever

gear

screw
Solution

The six types of simple machines are the lever, wheel and axle, pulley, inclined plane, wedge, and screw.

2 If 65 lbs. of force is applied 5 ft. from the fulcrum at the blue arrow and the green box is 4 ft. from the fulcrum, how much would the green box have to weigh to balance the lever?
62% Answer Correctly
162.5 lbs.
81.25 lbs.
20.31 lbs.
243.75 lbs.
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 Ra, our missing value, and plugging in our variables yields:

Ra = \( \frac{R_bd_b}{d_a} \) = \( \frac{65 lbs. \times 5 ft.}{4 ft.} \) = \( \frac{325 ft⋅lb}{4 ft.} \) = 81.25 lbs.

3

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

50% Answer Correctly

wheel and axle

first-class lever

block and tackle

inclined plane
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.

4

An inclined plane increases ___________ to reduce ____________.

58% Answer Correctly

force, power

distance, force

force, distance

distance, power
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.

5 What's the mechanical advantage of a wedge that's 2 inches wide and 18 inches long?
83% Answer Correctly
9.9
1
13.5
9
Solution

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

MA = \( \frac{l}{t} \) = \( \frac{18 in.}{2 in.} \) = 9