ASVAB Mechanical Comprehension Practice Test 479464 Results

Your Results Global Average
Questions 5 5
Correct 0 3.10
Score 0% 62%

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

everywhere in the system

the portions of the system at an altitude below the input

all of these are correct

the portions of the system at an altitude above 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

Which of the following will increase the mechanical advantage of a second-class lever?

55% Answer Correctly

move the object being lifted farther away from the fulcrum

move the fulcrum between the force and the object being lifted

move the object being lifted closer to the fulcrum

decrease the length of the lever


Solution

A second-class lever is used to increase force on an object in the same direction as the force is applied. This lever requires a smaller force to lift a larger load but the force must be applied over a greater distance. The fulcrum is placed at one end of the lever and mechanical advantage increases as the object being lifted is moved closer to the fulcrum or the length of the lever is increased. An example of a second-class lever is a wheelbarrow.


3 What's the mechanical advantage of a wedge that's 2 inches wide and 14 inches long?
83% Answer Correctly
9
7.7
10.5
7

Solution

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

MA = \( \frac{l}{t} \) = \( \frac{14 in.}{2 in.} \) = 7


4

Which of the following statements about this pulley configuration is false?

48% Answer Correctly

Mechanical advantage is the number of ropes that support the resistance

Changes the direction of and multiplies the effort force

This is a block and tackle pulley configuration

Only multiplies the effort force


Solution

A block and tackle is a combination of one or more fixed pulleys and one or more movable pulleys where the fixed pulleys change the direction of the effort force and the movable pulleys multiply it. The mechanical advantage is equal to the number of times the effort force changes direction and can be increased by adding more pulley wheels to the system. An easy way to find the mechanical advantage of a block and tackle pulley system is to count the number of ropes that support the resistance.


5

Which of these is the formula for kinetic energy?

68% Answer Correctly

\(KE = {1 \over 2}mv^2\)

\(KE = {1 \over 2}mh^2\)

\(KE = mgh\)

\(KE = {m \over v^2 }\)


Solution

Kinetic energy is the energy of movement and is a function of the mass of an object and its speed: \(KE = {1 \over 2}mv^2\) where m is mass in kilograms, v is speed in meters per second, and KE is in joules. The most impactful quantity to kinetic energy is velocity as an increase in mass increases KE linearly while an increase in speed increases KE exponentially.