ASVAB Mechanical Comprehension Practice Test 778040 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.47
Score	0%	69%

Review

Collinear forces:

72% Answer Correctly

	act in a common plane
	act along the same line of action
	are unrelated to each other
	pass through a common point

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.

Which of the following will increase the mechanical advantage of this inclined plane?

58% Answer Correctly

	lengthen the ramp
	shorten the ramp
	increase the force acting at the blue arrow
	lower the force acting at the blue arrow

Solution

The mechanical advantage (MA) of an inclined plane is the effort distance divided by the resistance distance. In order to increase mechanical advantage, this ratio must increase which means making the effort distance longer and this can be accomplished by lengthening the length of the ramp.

Two gears are connected and the larger gear drives the smaller gear. The speed of rotation will __________ and the torque will __________.

61% Answer Correctly

	increase, decrease
	decrease, decrease
	increase, increase
	decrease, increase

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.

4 If input effort is 800 ft⋅lb, what output effort will be produced by a machine with a mechanical advantage of 2?

79% Answer Correctly

	400ft⋅lb
	800ft⋅lb
	3200ft⋅lb
	1600 ft⋅lb

Solution

Mechanical advantage is the ratio of output force to input force and tells us by how many times a machine multiplies input effort. So, a machine with a mechanical advantage of 2 will multiply an input effort of 800 ft⋅lb by 2 to produce an output effort of 1600 ft⋅lb.

5 How much resistance could a 250 lb. effort force lift using a block and tackle pulley that has 10 ropes supporting the resistance?

80% Answer Correctly

	2502 lbs.
	2504 lbs.
	2500 lbs.
	2250 lbs.

Solution

The mechanical advantage (MA) of a block and tackle pulley is equal to the number of times the effort force changes direction. An easy way to count how many times the effort force changes direction is to count the number of ropes that support the resistance which, in this problem, is 10. With a MA of 10, a 250 lbs. effort force could lift 250 lbs. x 10 = 2500 lbs. resistance.