ASVAB Mechanical Comprehension Practice Test 320193 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.64
Score	0%	53%

Review

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

52% Answer Correctly

	4950 ft⋅lb
	6 ft⋅lb
	12 ft⋅lb
	1 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:
\( W = 3 hp \times 550 \frac{ft⋅lb}{s} \times 3s = 4950 ft⋅lb \)

The principle of conservation of mechanical energy states that, as long as no other forces are applied, what will remain constant as an object falls?

45% Answer Correctly

	total mechanical energy
	acceleration
	potential energy
	kinetic energy

Solution

As an object falls, its potential energy is converted into kinetic energy. The principle of conservation of mechanical energy states that, as long as no other forces are applied, total mechanical energy (PE + KE) of the object will remain constant at all points in its descent.

What type of load is sudden and for a relatively short duration?

70% Answer Correctly

	dynamic load
	non-uniformly distributed load
	impact load
	concentrated 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 What is the power output of a 3 hp engine that's 95% efficient?

40% Answer Correctly

	391.9 \( \frac{ft⋅lb}{s} \)
	285 \( \frac{ft⋅lb}{s} \)
	1567.5 \( \frac{ft⋅lb}{s} \)
	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 3 hp x 550 \( \frac{ft⋅lb}{s} \) = 1650 \( \frac{ft⋅lb}{s} \)
\( P_{o} = \frac{E \times P_{i}}{100} = \frac{95 \times 1650 \frac{ft⋅lb}{s}}{100} \) \( = \frac{156750 \frac{ft⋅lb}{s}}{100} \) = 1567.5 \( \frac{ft⋅lb}{s} \)

Specific gravity is a comparison of the density of an object with the density of:

57% Answer Correctly

	water
	air
	oil
	carbon

Solution

Specific gravity is the ratio of the density of equal volumes of a substance and water and is measured by a hyrdometer.