ASVAB Mechanical Comprehension Practice Test 981011 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.82
Score	0%	56%

Review

The measure of how much of the power put into a machine is turned into movement or force is called:

56% Answer Correctly

	force multiplication
	power
	mechanical advantage
	efficiency

Solution

The efficiency of a machine describes how much of the power put into the machine is turned into movement or force. A 100% efficient machine would turn all of the input power into output movement or force. However, no machine is 100% efficient due to friction, heat, wear and other imperfections that consume input power without delivering any output.

The principle of conservation of mechanical energy states that, as long as no other forces are applied, what will remain constant as an object falls?

45% Answer Correctly

	acceleration
	kinetic energy
	total mechanical energy
	potential energy

Solution

As an object falls, its potential energy is converted into kinetic energy. The principle of conservation of mechanical energy states that, as long as no other forces are applied, total mechanical energy (PE + KE) of the object will remain constant at all points in its descent.

Connected gears of different numbers of teeth are used together to change which of the following charasteristics of the input force?

65% Answer Correctly

	energy
	rotational direction
	force
	torque

Solution

Connected gears of different numbers of teeth are used together to change the rotational speed and torque of the input force. If the smaller gear drives the larger gear, the speed of rotation will be reduced and the torque will increase. If the larger gear drives the smaller gear, the speed of rotation will increase and the torque will be reduced.

Lisa lifts a 25 pound box from the floor onto a loading dock 4 ft. off the ground. Sam slides the same box along a ramp to move it up another 4 ft. onto a flatbed truck. Who has done more work?

50% Answer Correctly

	Neither have done any work
	They have done an equal amount of work
	Sam
	Lisa

Solution

Work is force multiplied by distance. Because both Connie and Sam moved the same weight the same distance they have done an equal amount of work. Sam employed the mechnacial advantage of an inclined plane so he exerted less effort to do the work but the amount of work done was still the same.

5 A = 7 ft., the green box weighs 25 lbs., and the blue box weighs 70 lbs. What does distance B need to be for this lever to balance?

65% Answer Correctly

	490 ft.
	5 ft.
	2.5 ft.
	0.83 ft.

Solution

In order for this lever to balance, the torque acting on side A must equal the torque acting on side B. 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

For this problem, the equation becomes:

25 lbs. x 7 ft. = 70 lbs. x d_B

d_B = \( \frac{25 \times 7 ft⋅lb}{70 lbs.} \) = \( \frac{175 ft⋅lb}{70 lbs.} \) = 2.5 ft.