ASVAB Mechanical Comprehension Practice Test 919775 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.95
Score	0%	59%

Review

1 What is the power output of a 7 hp engine that's 40% efficient?

40% Answer Correctly

	1540 \( \frac{ft⋅lb}{s} \)
	3080 \( \frac{ft⋅lb}{s} \)
	385 \( \frac{ft⋅lb}{s} \)
	770 \( \frac{ft⋅lb}{s} \)

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 7 hp x 550 \( \frac{ft⋅lb}{s} \) = 3850 \( \frac{ft⋅lb}{s} \)
\( P_{o} = \frac{E \times P_{i}}{100} = \frac{40 \times 3850 \frac{ft⋅lb}{s}}{100} \) \( = \frac{154000 \frac{ft⋅lb}{s}}{100} \) = 1540 \( \frac{ft⋅lb}{s} \)

Which of the following surfaces would have the highest coefficient of friction?

77% Answer Correctly

	concrete
	ice
	steel
	marble

Solution

Coefficient of friction (μ) represents how much two materials resist sliding across each other. Smooth surfaces like ice have low coefficients of friction while rough surfaces like concrete have high μ.

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

	potential energy
	kinetic energy
	acceleration
	total mechanical 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.

Which of the following statements about drag is false?

58% Answer Correctly

	the amount of drag depends on the shape of an object
	the amount of drag depends on the speed of an object
	slower objects experience more drag than faster objects
	drag occurs during movement through a fluid

Solution

Drag is friction that opposes movement through a fluid like liquid or air. The amount of drag depends on the shape and speed of the object with slower objects experiencing less drag than faster objects and more aerodynamic objects experiencing less drag than those with a large leading surface area.

The standard unit of energy is the:

73% Answer Correctly

	Horsepower
	Joule
	Watt
	Volt

Solution

The Joule (J) is the standard unit of energy and has the unit \({kg \times m^2} \over s^2\).