ASVAB Mechanical Comprehension Practice Test 302999 Results

Your Results Global Average
Questions 5 5
Correct 0 3.07
Score 0% 61%

Review

1

Friction between two or more solid objects that are not moving relative to each other is called:

74% Answer Correctly

gravitational friction

static friction

dynamic friction

kinetic friction


Solution

Static friction is friction between two or more solid objects that are not moving relative to each other. An example is the friction that prevents a box on a sloped surface from sliding farther down the surface.


2

The mechanical advantage of a third class lever is always:

37% Answer Correctly

equal to one

not equal to one

less than one

greater than one


Solution

A third class lever is designed to multiply distance and speed at the expense of effort force. Because the effort force is greater than the resistance, the mechanical advantage of a third class lever is always less than one.

An example of a third class lever is a broom. The fulcrum is at your hand on the end of the broom, the effort force is your other hand in the middle, and the resistance is at the bottom bristles. The effort force of your hand in the middle multiplies the distance and speed of the bristles at the bottom but at the expense of producing a brushing force that's less than the force you're applying with your hand.


3

Hydraulics is the transmission of force through the use of which of the following?

74% Answer Correctly

torque

gear systems

air pressure

liquids


Solution

Hydraulics is the transmission of force through the use of liquids. Liquids are especially suited for transferring force in complex machines because they compress very little and can occupy very small spaces. Hydraulic pressure is calculated by dividing force by the area over which it is applied: P = F/A where F is force in pounds, A is area in square inches, and the resulting pressure is in pounds per square inch (psi).


4

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

59% Answer Correctly

lengthen the ramp

shorten the ramp

increase the force acting at the blue arrow

lower the force acting at the blue arrow


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.


5

The mechanical advantage of a wheel and axle is equal to the:

61% Answer Correctly

length of the axle

difference in the lengths of the axles

ratio of the diameters of the wheels

difference in the diameters of the wheels


Solution

A wheel and axle uses two different diameter wheels mounted to a connecting axle. Force is applied to the larger wheel and large movements of this wheel result in small movements in the smaller wheel. Because a larger movement distance is being translated to a smaller distance, force is increased with a mechanical advantage equal to the ratio of the diameters of the wheels. An example of a wheel and axle is the steering wheel of a car.