ASVAB Mechanical Comprehension Practice Test 871022 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.90
Score	0%	58%

Review

Concurrent forces:

55% Answer Correctly

	act in a common plane
	act along the same line of action
	pass through a common point
	act in a common dimension

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.

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

	the portions of the system at an altitude below the input
	everywhere in the system
	the portions of the system at an altitude above the input
	all of these are correct

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.

Sam can do 50 ft. lb. of work in 2 minutes and 5 seconds. What would Sam have to do to increase his power output?

64% Answer Correctly

	do the work in 3 minutes
	do the work in 2 minutes
	do 25 ft. lb. of work in 2 minutes 5 seconds
	do 100 ft. lb. of work in 4 minutes 12 seconds

Solution

Power is the rate of doing work or \(\frac{W}{t}\). To increase power, increase the work being done in the same amount of time or do the same amount of work in less time.

4 If the green box weighs 35 lbs. and is 7 ft. from the fulcrum, how far from the fulcrum would a 55 lbs. weight need to be placed to balance the lever?

61% Answer Correctly

	4.45 ft.
	245 ft.
	13.36 ft.
	5 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_b, our missing value, and plugging in our variables yields:

d_b = \( \frac{R_ad_a}{R_b} \) = \( \frac{35 lbs. \times 7 ft.}{55 lbs.} \) = \( \frac{245 ft⋅lb}{55 lbs.} \) = 4.45 ft.

The principle of moments defines equilibrium in terms of:

53% Answer Correctly

	speed
	power
	torque
	energy

Solution

According to the principle of moments, you can maintain equilibrium if the moments (forces) tending to clockwise rotation are equal to the moments tending to counterclockwise rotation. Another name for these moments of force is torque.