ASVAB Mechanical Comprehension Practice Test 563529 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.02
Score	0%	60%

Review

What type of load varies with time or affects a structure that experiences a high degree of movement?

65% Answer Correctly

	dynamic load
	static load
	impact load
	concentrated load

Solution

A concentrated load acts on a relatively small area of a structure, a static uniformly distributed load doesn't create specific stress points or vary with time, a dynamic load varies with time or affects a structure that experiences a high degree of movement, an impact load is sudden and for a relatively short duration and a non-uniformly distributed load creates different stresses at different locations on a structure.

Concurrent forces:

55% Answer Correctly

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

3 If the force applied at the blue arrow over 2 ft. moves the green box 0.22 ft., what is the mechanical advantage of this lever?

56% Answer Correctly

	9
	8.1
	9.9
	18

Solution

Mechanical advantage (MA) can be calculated knowing only the distance the effort (blue arrow) moves and the distance the resistance (green box) moves. The equation is:

MA = \( \frac{E_d}{R_d} \)

where E_d is the effort distance and R_d is the resistance distance. For this problem, the equation becomes:

MA = \( \frac{2 ft.}{0.22 ft.} \) = 9

You might be wondering how having an effort distance of 9 times the resistance distance is an advantage. Remember the principle of moments. For a lever in equilibrium the effort torque equals the resistance torque. Because torque is force x distance, if the effort distance is 9 times the resistance distance, the effort force must be \( \frac{1}{9} \) the resistance force. You're trading moving 9 times the distance for only having to use \( \frac{1}{9} \) the force.

4 If A = 10 ft., B = 3 ft., C = 6 ft., the green box weighs 35 lbs. and the blue box weighs 45 lbs., what does the orange box have to weigh for this lever to balance?

43% Answer Correctly

	35.83 lbs.
	71.67 lbs.
	17.92 lbs.
	0 lbs.

Solution

In order for this lever to balance, the torque acting on each side of the fulrum must be equal. So, the torque produced by A must equal the torque produced by B and C. Torque is weight x distance from the fulcrum which means that the following must be true for the lever to balance:

f_Ad_A = f_Bd_B + f_Cd_C

For this problem, this equation becomes:

35 lbs. x 10 ft. = 45 lbs. x 3 ft. + f_C x 6 ft.

350 ft. lbs. = 135 ft. lbs. + f_C x 6 ft.

f_C = \( \frac{350 ft. lbs. - 135 ft. lbs.}{6 ft.} \) = \( \frac{215 ft. lbs.}{6 ft.} \) = 35.83 lbs.

The force amplification achieved by using a tool, mechanical device or machine system is called:

80% Answer Correctly

	power
	work
	mechanical advantage
	efficiency

Solution

Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. Such a device utilizes input force and trades off forces against movement to amplify and/or change its direction.