ASVAB Mechanical Comprehension Practice Test 570609 Results

Your Results Global Average
Questions 5 5
Correct 0 2.78
Score 0% 56%

Review

1

For a hydraulic system, pressure applied to the input of the system will increase the pressure in which parts of the system?

58% Answer Correctly

all of these are correct

everywhere in the system

the portions of the system at an altitude above the input

the portions of the system at an altitude below the input


Solution

Pascal's law states that a pressure change occurring anywhere in a confined incompressible fluid is transmitted throughout the fluid such that the same change occurs everywhere. For a hydraulic system, this means that a pressure applied to the input of the system will increase the pressure everywhere in the system.


2 If the green box weighs 55 lbs. and 75 lbs. of force is applied 5 ft. from the fulcrum at the blue arrow, how far from the fulcrum would the green box need to be placed to balance the lever?
55% Answer Correctly
11 ft.
13.64 ft.
6.82 ft.
20.45 ft.

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

da = \( \frac{R_bd_b}{R_a} \) = \( \frac{75 lbs. \times 5 ft.}{55 lbs.} \) = \( \frac{375 ft⋅lb}{55 lbs.} \) = 6.82 ft.


3

Specific gravity is a comparison of the density of an object with the density of:

57% Answer Correctly

water

carbon

air

oil


Solution

Specific gravity is the ratio of the density of equal volumes of a substance and water and is measured by a hyrdometer.


4

An inclined plane increases ___________ to reduce ____________.

58% Answer Correctly

distance, power

force, power

distance, force

force, distance


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

Lisa lifts a 25 pound box from the floor onto a loading dock 4 ft. off the ground. Sam slides the same box along a ramp to move it up another 4 ft. onto a flatbed truck. Who has done more work?

50% Answer Correctly

Sam

Lisa

Neither have done any work

They have done an equal amount of work


Solution

Work is force multiplied by distance. Because both Connie and Sam moved the same weight the same distance they have done an equal amount of work. Sam employed the mechnacial advantage of an inclined plane so he exerted less effort to do the work but the amount of work done was still the same.