ASVAB Mechanical Comprehension Practice Test 494963 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.84
Score	0%	57%

Review

The mechanical advantage of a wheel and axle is equal to the:

61% Answer Correctly

	difference in the lengths of the axles
	difference in the diameters of the wheels
	ratio of the diameters of the wheels
	length of the axle

Solution

A wheel and axle uses two different diameter wheels mounted to a connecting axle. Force is applied to the larger wheel and large movements of this wheel result in small movements in the smaller wheel. Because a larger movement distance is being translated to a smaller distance, force is increased with a mechanical advantage equal to the ratio of the diameters of the wheels. An example of a wheel and axle is the steering wheel of a car.

What type of load varies with time or affects a structure that experiences a high degree of movement?

65% Answer Correctly

	impact load
	dynamic load
	concentrated load
	static load

Solution

A concentrated load acts on a relatively small area of a structure, a static uniformly distributed load doesn't create specific stress points or vary with time, a dynamic load varies with time or affects a structure that experiences a high degree of movement, an impact load is sudden and for a relatively short duration and a non-uniformly distributed load creates different stresses at different locations on a structure.

3 If this lever is in equilibrium with an effort force of 6.67 ft. lb. at the blue arrow and a resistance force of 2 ft. lb. at the green box, what is its mechanical advantage?

48% Answer Correctly

	0.27
	0.3
	0.1
	2.3

Solution

Mechanical advantage (MA) is the ratio by which effort force relates to resistance force. If both forces are known, calculating MA is simply a matter of dividing resistance force by effort force:

MA = \( \frac{F_r}{F_e} \) = \( \frac{2 ft.}{6.67 ft.} \) = 0.3

In this case, the mechanical advantage is less than one meaning that each unit of effort force results in just 0.3 units of resistance force. However, a third class lever like this isn't designed to multiply force like a first class lever. A third class lever is designed to multiply distance and speed at the resistance by sacrificing force at the resistance. Different lever styles have different purposes and multiply forces in different ways.

4 How much work can a 3 hp engine do in 5 seconds?

52% Answer Correctly

	8250 ft⋅lb
	12 ft⋅lb
	1 ft⋅lb
	0 ft⋅lb

Solution

Horsepower (hp) is a common measure of power output for complex machines. By definition, a 1 hp machine does 550 ft⋅lb of work in 1 second: 1 hp = 550 ft⋅lb/s. Substituting the variables for this problem gives us:
\( W = 3 hp \times 550 \frac{ft⋅lb}{s} \times 5s = 8250 ft⋅lb \)

The science that deals with motion and the forces that produce motion is called which of the following?

57% Answer Correctly

	physics
	mechanics
	aeronautics
	engineering

Solution

Mechanics deals with motion and the forces that produce motion.