ASVAB Mechanical Comprehension Practice Test 858544 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.91
Score	0%	58%

Review

1 What is the power output of a 6 hp engine that's 95% efficient?

40% Answer Correctly

	3135 \( \frac{ft⋅lb}{s} \)
	1567.5 \( \frac{ft⋅lb}{s} \)
	9405 \( \frac{ft⋅lb}{s} \)
	6270 \( \frac{ft⋅lb}{s} \)

Solution

\( Efficiency = \frac{Power_{out}}{Power_{in}} \times 100 \)
Solving for power out: \( P_{o} = \frac{E \times P_{i}}{100} \)
Knowing that 1 hp = 550 \( \frac{ft⋅lb}{s} \), P_i becomes 6 hp x 550 \( \frac{ft⋅lb}{s} \) = 3300 \( \frac{ft⋅lb}{s} \)
\( P_{o} = \frac{E \times P_{i}}{100} = \frac{95 \times 3300 \frac{ft⋅lb}{s}}{100} \) \( = \frac{313500 \frac{ft⋅lb}{s}}{100} \) = 3135 \( \frac{ft⋅lb}{s} \)

2 If the radius of the axle is 7 and the radius of the wheel is 10, what is the mechanical advantage of this wheel and axle configuration?

36% Answer Correctly

	1
	3
	-3
	1

Solution

The mechanical advantage of a wheel and axle lies in the difference in radius between the inner (axle) wheel and the outer wheel. But, this mechanical advantage is only realized when the input effort and load are applied to different wheels. Applying both input effort and load to the same wheel results in a mechanical advantage of 1.

What type of load acts on a relatively small area of a structure?

75% Answer Correctly

	concentrated load
	non-uniformly distributed load
	impact load
	dynamic 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.

4 If you lift a 28 lbs. rock 7 ft. from the ground, how much work have you done?

70% Answer Correctly

	392 ft⋅lb
	35 ft⋅lb
	21 ft⋅lb
	196 ft⋅lb

Solution

Work is force times distance. In this case, the force is the weight of the rock so:
\( W = F \times d \)
\( W = 28 \times 7 \)
\( W = 196 \)

A fixed pulley has a mechanical advantage of:

68% Answer Correctly

	2
	-1
	1
	0

Solution

A fixed pulley is used to change the direction of a force and does not multiply the force applied. As such, it has a mechanical advantage of one. The benefit of a fixed pulley is that it can allow the force to be applied at a more convenient angle, for example, pulling downward or horizontally to lift an object instead of upward.