ASVAB Mechanical Comprehension Practice Test 513408 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.87
Score	0%	57%

Review

Which of the following is not a type of simple machine?

58% Answer Correctly

	lever
	pulley
	screw
	gear

Solution

The six types of simple machines are the lever, wheel and axle, pulley, inclined plane, wedge, and screw.

Coplanar forces:

61% Answer Correctly

	act along the same line of action
	have opposite dimensions
	pass through a common point
	act in a common plane

Solution

Collinear forces act along the same line of action, concurrent forces pass through a common point and coplanar forces act in a common plane.

3 The green box weighs 60 lbs. and a 35 lbs. weight is placed 9 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?

57% Answer Correctly

	10.5 ft.
	21 ft.
	540 ft.
	5.25 ft.

Solution

To balance this lever the torques on each side of the fulcrum must be equal. Torque is weight x distance from the fulcrum so the equation for equilibrium is:

R_ad_a = R_bd_b

where a represents the left side of the fulcrum and b the right, R is resistance (weight) and d is the distance from the fulcrum.

Solving for d_a, our missing value, and plugging in our variables yields:

d_a = \( \frac{R_bd_b}{R_a} \) = \( \frac{35 lbs. \times 9 ft.}{60 lbs.} \) = \( \frac{315 ft⋅lb}{60 lbs.} \) = 5.25 ft.

4 If the radius of the axle is 7 and the radius of the wheel is 12, what is the mechanical advantage of this wheel and axle configuration?

52% Answer Correctly

	7
	12
	1.71
	0.58

Solution

The mechanical advantage of a wheel and axle is the input radius divided by the output radius:

MA = \( \frac{r_i}{r_o} \)

In this case, the input radius (where the effort force is being applied) is 12 and the output radius (where the resistance is being applied) is 7 for a mechanical advantage of \( \frac{12}{7} \) = 1.71

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
	the portions of the system at an altitude above the input
	everywhere in the system
	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.