ASVAB Mechanical Comprehension Practice Test 379908 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.39
Score	0%	68%

Review

1 If you lift a 20 lbs. rock 4 ft. from the ground, how much work have you done?

71% Answer Correctly

	160 ft⋅lb
	40 ft⋅lb
	None of these is correct
	80 ft⋅lb

Solution

Work is force times distance. In this case, the force is the weight of the rock so:
\( W = F \times d \)
\( W = 20 \times 4 \)
\( W = 80 \)

The work done by the sum of all forces acting on a particle equals the change in the kinetic energy of the particle. This defines which of the following?

60% Answer Correctly

	Pascal's law
	mechanical advantage
	work-energy theorem
	conservation of mechanical energy

Solution

The work-energy theorem states that the work done by the sum of all forces acting on a particle equals the change in the kinetic energy of the particle. Simply put, work imparts kinetic energy to the matter upon which the work is being done.

The standard unit of energy is the:

73% Answer Correctly

	Volt
	Watt
	Joule
	Horsepower

Solution

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

The principle of moments defines equilibrium in terms of:

53% Answer Correctly

	torque
	energy
	power
	speed

Solution

According to the principle of moments, you can maintain equilibrium if the moments (forces) tending to clockwise rotation are equal to the moments tending to counterclockwise rotation. Another name for these moments of force is torque.

5 20 lbs. of effort is used by a machine to lift a 140 lbs. box. What is the mechanical advantage of the machine?

84% Answer Correctly

	7
	-1
	9
	3

Solution

Mechanical advantage is resistance force divided by effort force:

MA = \( \frac{F_r}{F_e} \) = \( \frac{140 lbs.}{20 lbs.} \) = 7