ASVAB Mechanical Comprehension Practice Test 968381 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.22
Score	0%	64%

Review

1 A 340 lb. barrel is rolled up a 6 ft. ramp to a platform that's 1 ft. tall. What effort is required to move the barrel?

53% Answer Correctly

	53.7 lbs.
	113.3 lbs.
	62.3 lbs.
	56.7 lbs.

Solution

This problem describes an inclined plane and, for an inclined plane, the effort force multiplied by the effort distance equals the resistance force multipied by the resistance distance:

F_ed_e = F_rd_r

Plugging in the variables from this problem yields:

F_e x 6 ft. = 340 lbs. x 1 ft.
F_e = \( \frac{340 ft⋅lb}{6 ft.} \) = 56.7 lbs.

A watt is the unit for which of the following?

71% Answer Correctly

	mechanical advantage
	work
	power
	energy

Solution

Power is the rate at which work is done, P = w/t, or work per unit time. The watt (W) is the unit for power and is equal to 1 joule (or newton-meter) per second. Horsepower (hp) is another familiar unit of power used primarily for rating internal combustion engines. 1 hp equals 746 watts.

3 If you have a gear train with two gears, the first with 20 teeth and the second with 4 teeth, how many revolutions does the second gear make for each revolution of the first gear?

77% Answer Correctly

	5
	6.5
	7.5
	2.5

Solution

The gear ratio (V_r) of a gear train is the product of the gear ratios between the pairs of meshed gears. Let N represent the number of teeth for each gear:

V_r = \( \frac{N_1}{N_2} \) \( \frac{N_2}{N_3} \) \( \frac{N_3}{N_4} \) ... \( \frac{N_n}{N_{n+1}} \)

In this problem, we have only two gears so the equation becomes:

V_r = \( \frac{N_1}{N_2} \) = \( \frac{20}{4} \) = 5

Coplanar forces:

61% Answer Correctly

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

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 statements about drag is false?

58% Answer Correctly

	drag occurs during movement through a fluid
	slower objects experience more drag than faster objects
	the amount of drag depends on the shape of an object
	the amount of drag depends on the speed of an object

Solution

Drag is friction that opposes movement through a fluid like liquid or air. The amount of drag depends on the shape and speed of the object with slower objects experiencing less drag than faster objects and more aerodynamic objects experiencing less drag than those with a large leading surface area.