ASVAB Mechanical Comprehension Practice Test 991875 Results

Your Results Global Average
Questions 5 5
Correct 0 3.01
Score 0% 60%

Review

1

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

57% Answer Correctly

along

perpendicular to

opposite to

parallel 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.


2

Which of the following will increase the mechanical advantage of this inclined plane?

59% Answer Correctly

shorten the ramp

lower the force acting at the blue arrow

increase the force acting at the blue arrow

lengthen the ramp


Solution

The mechanical advantage (MA) of an inclined plane is the effort distance divided by the resistance distance. In order to increase mechanical advantage, this ratio must increase which means making the effort distance longer and this can be accomplished by lengthening the length of the ramp.


3

The mass of an object correlates to the size of the object but ultimately depends on:

66% Answer Correctly

the object's density

the object's weight

gravity

the object's potential energy


Solution

Mass is a measure of the amount of matter in an object.  In general, larger objects have larger mass than smaller objects but mass ultimately depends on how compact (dense) a substance is.


4 If the green box weighs 45 lbs. and is 5 ft. from the fulcrum, how much force would need to be applied at the blue arrow to balance the lever if the arrow's distance from the fulcrum is 6 ft.?
62% Answer Correctly
75 lbs.
270 lbs.
9.38 lbs.
37.5 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 Rb, our missing value, and plugging in our variables yields:

Rb = \( \frac{R_ad_a}{d_b} \) = \( \frac{45 lbs. \times 5 ft.}{6 ft.} \) = \( \frac{225 ft⋅lb}{6 ft.} \) = 37.5 lbs.


5

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 applied force

decrease torque

increase torque

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).