ASVAB Mechanical Comprehension Practice Test 669173 Results

Your Results Global Average
Questions 5 5
Correct 0 3.30
Score 0% 66%

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

Torque involves a perpendicular force applied to a lever arm that moves around a center of rotation. Increasing the length of the lever arm will do which of the following?

54% Answer Correctly

decrease torque

increase torque

decrease applied force

increase applied force
Solution

Torque measures force applied during rotation: τ = rF.  Torque (τ, the Greek letter tau) = the radius of the lever arm (r) multiplied by the force (F) applied. Radius is measured from the center of rotation or fulcrum to the point at which the perpendicular force is being applied. The resulting unit for torque is newton-meter (N-m) or foot-pound (ft-lb).

3

Which of the following surfaces would have the lowest coefficient of friction?

85% Answer Correctly

ice

tile

leather

concrete
Solution

Coefficient of friction (μ) represents how much two materials resist sliding across each other.  Smooth surfaces like ice have low coefficients of friction while rough surfaces like concrete have high μ.

4 If a 10 lbs. weight is placed 5 ft. from the fulcrum at the blue arrow and the green box is 8 ft. from the fulcrum, how much would the green box have to weigh to balance the lever?
61% Answer Correctly
3.13 lbs.
6.25 lbs.
0 lbs.
18.75 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 Ra, our missing value, and plugging in our variables yields:

Ra = \( \frac{R_bd_b}{d_a} \) = \( \frac{10 lbs. \times 5 ft.}{8 ft.} \) = \( \frac{50 ft⋅lb}{8 ft.} \) = 6.25 lbs.

5

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

70% Answer Correctly

second-class lever

inclined plane

first-class lever

third-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.