ASVAB Mechanical Comprehension Practice Test 337470 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.68
Score	0%	54%

Review

1 What is the power output of a 9 hp engine that's 70% efficient?

40% Answer Correctly

	7 \( \frac{ft⋅lb}{s} \)
	3465 \( \frac{ft⋅lb}{s} \)
	1732.5 \( \frac{ft⋅lb}{s} \)
	6930 \( \frac{ft⋅lb}{s} \)

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 9 hp x 550 \( \frac{ft⋅lb}{s} \) = 4950 \( \frac{ft⋅lb}{s} \)
\( P_{o} = \frac{E \times P_{i}}{100} = \frac{70 \times 4950 \frac{ft⋅lb}{s}}{100} \) \( = \frac{346500 \frac{ft⋅lb}{s}}{100} \) = 3465 \( \frac{ft⋅lb}{s} \)

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

	kinetic energy
	total mechanical energy
	potential energy
	acceleration

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.

3 The radius of the axle is 3, the radius of the wheel is 4, and the blue box weighs 40 lbs. What is the effort force necessary to balance the load?

53% Answer Correctly

	30.08 lbs.
	7 lbs.
	5.33 lbs.
	4.33 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 4 and the output radius (where the resistance is being applied) is 3 for a mechanical advantage of \( \frac{4}{3} \) = 1.33

MA = \( \frac{load}{effort} \) so effort = \( \frac{load}{MA} \) = \( \frac{40 lbs.}{1.33} \) = 30.08 lbs.

Which of the following is not a characteristic of a ceramic?

61% Answer Correctly

	low corrosive action
	chemically stable
	low density
	high melting point

Solution

Ceramics are mixtures of metallic and nonmetallic elements that withstand exteme thermal, chemical, and pressure environments. They have a high melting point, low corrosive action, and are chemically stable. Examples include rock, sand, clay, glass, brick, and porcelain.

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

69% Answer Correctly

	dynamic load
	impact load
	non-uniformly distributed 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.