ASVAB Mechanical Comprehension Practice Test 306012 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.38
Score	0%	68%

Review

1 The radius of the axle is 5, the radius of the wheel is 8, and the blue box weighs 55 lbs. What is the effort force necessary to balance the load?

53% Answer Correctly

	13 lbs.
	34.38 lbs.
	40 lbs.
	5 lbs.

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 8 and the output radius (where the resistance is being applied) is 5 for a mechanical advantage of \( \frac{8}{5} \) = 1.6

MA = \( \frac{load}{effort} \) so effort = \( \frac{load}{MA} \) = \( \frac{55 lbs.}{1.6} \) = 34.38 lbs.

What is work?

60% Answer Correctly

	The movement of an object by a force
	The potential for exertion
	Force per unit distance
	Force per unit time

Solution

Work is accomplished when force is applied to an object: W = Fd where F is force in newtons (N) and d is distance in meters (m). Thus, the more force that must be applied to move an object, the more work is done and the farther an object is moved by exerting force, the more work is done. By definition, work is the displacement of an object resulting from applied force.

One Horsepower (hp) is equal to how many watts?

76% Answer Correctly

	1492
	746
	1
	9.8

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.

4 If input effort is 700 ft⋅lb, what output effort will be produced by a machine with a mechanical advantage of 9?

79% Answer Correctly

	0ft⋅lb
	1575ft⋅lb
	25200ft⋅lb
	6300 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 9 will multiply an input effort of 700 ft⋅lb by 9 to produce an output effort of 6300 ft⋅lb.

A wedge is most similar to what other type of simple machine?

70% Answer Correctly

	third-class lever
	first-class lever
	second-class lever
	inclined plane

Solution

The wedge is a moving inclined plane that is used to lift, hold, or break apart an object. A wedge converts force applied to its blunt end into force perpendicular to its inclined surface. In contrast to a stationary plane where force is applied to the object being moved, with a wedge the object is stationary and the force is being applied to the plane. Examples of a wedge include knives and chisels.