ASVAB Mechanical Comprehension Practice Test 7220 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.45
Score	0%	69%

Review

1 If the radius of the axle is 7 and the radius of the wheel is 12, what is the mechanical advantage of this wheel and axle configuration?

52% Answer Correctly

	12
	1.71
	0.58
	5

Solution

The mechanical advantage of a wheel and axle is the input radius divided by the output radius:

MA = \( \frac{r_i}{r_o} \)

In this case, the input radius (where the effort force is being applied) is 12 and the output radius (where the resistance is being applied) is 7 for a mechanical advantage of \( \frac{12}{7} \) = 1.71

2 50 lbs. of effort is used by a machine to lift a 400 lbs. box. What is the mechanical advantage of the machine?

84% Answer Correctly

	16
	4
	2
	8

Solution

Mechanical advantage is resistance force divided by effort force:

MA = \( \frac{F_r}{F_e} \) = \( \frac{400 lbs.}{50 lbs.} \) = 8

3 A 230 lb. barrel is rolled up a 8 ft. ramp to a platform that's 2 ft. tall. What effort is required to move the barrel?

53% Answer Correctly

	57.5 lbs.
	63.3 lbs.
	172.5 lbs.
	54.5 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 8 ft. = 230 lbs. x 2 ft.
F_e = \( \frac{460 ft⋅lb}{8 ft.} \) = 57.5 lbs.

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

80% Answer Correctly

	work
	power
	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.

5 If A = 5 ft. and the green box weighs 10 lbs. what is the torque acting on the A side of this lever?

75% Answer Correctly

	50 ft⋅lb
	0 ft⋅lb
	16 ft⋅lb
	25 ft⋅lb

Solution

For a lever, torque is weight x distance from the fulcrum which, in this case, is: 10 ft. x 5 lbs. = 50 ft⋅lb