ASVAB Mechanical Comprehension Practice Test 161950 Results

Your Results Global Average
Questions 5 5
Correct 0 3.12
Score 0% 62%

Review

1

Assuming force applied remains constant, which of the following will result in more work being done?

53% Answer Correctly

moving the object with more speed

increasing the coefficient of friction

moving the object with more acceleration

moving the object farther


Solution

Work is accomplished when force is applied to an object: W = Fd where F is force in newtons (N) and d is distance in meters (m). Thus, the more force that must be applied to move an object, the more work is done and the farther an object is moved by exerting force, the more work is done.


2 If 50 lbs. of force is applied 5 ft. from the fulcrum at the blue arrow and the green box is 3 ft. from the fulcrum, how much would the green box have to weigh to balance the lever?
62% Answer Correctly
10 lbs.
250 lbs.
83.33 lbs.
0 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 Ra, our missing value, and plugging in our variables yields:

Ra = \( \frac{R_bd_b}{d_a} \) = \( \frac{50 lbs. \times 5 ft.}{3 ft.} \) = \( \frac{250 ft⋅lb}{3 ft.} \) = 83.33 lbs.


3

According to Boyle's law, for a fixed amount of gas kept at a fixed temperature, which of the following are inversely proportional?

63% Answer Correctly

pressure, density

pressure, volume

density, volume

volume, mass


Solution

Boyle's law states that "for a fixed amount of an ideal gas kept at a fixed temperature, pressure and volume are inversely proportional".


4

Which class of lever is used to increase force on an object in the same direction as the force is applied?

53% Answer Correctly

second

first

third

all of these


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.


5

When all forces acting on a system cancel each other out, this is called:

80% Answer Correctly

rest

equilibrium

stasis

potential energy


Solution

When a system is stable or balanced (equilibrium) all forces acting on the system cancel each other out. In the case of torque, equilibrium means that the sum of the anticlockwise moments about a center of rotation equal the sum of the clockwise moments.