ASVAB Mechanical Comprehension Practice Test 901574 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.90
Score	0%	58%

Review

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

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

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.

2 A 300 lb. barrel is rolled up a 15 ft. ramp to a platform that's 3 ft. tall. What effort is required to move the barrel?

53% Answer Correctly

	90 lbs.
	60 lbs.
	66 lbs.
	56 lbs.

Solution

This problem describes an inclined plane and, for an inclined plane, the effort force multiplied by the effort distance equals the resistance force multipied by the resistance distance:

F_ed_e = F_rd_r

Plugging in the variables from this problem yields:

F_e x 15 ft. = 300 lbs. x 3 ft.
F_e = \( \frac{900 ft⋅lb}{15 ft.} \) = 60 lbs.

The principle of moments defines equilibrium in terms of:

53% Answer Correctly

	torque
	power
	speed
	energy

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.

Which of the following represents how much two materials resist sliding across each other?

53% Answer Correctly

	normal friction
	static friction
	coefficient of friction
	kinetic friction

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.

5 If the green arrow in this diagram represents 760 ft⋅lb of work, how far will the box move if it weighs 190 pounds?

72% Answer Correctly

	0 ft.
	2 ft.
	95 ft.
	4 ft.

Solution

The Law of Work states that the work put into a machine is equal to the work received from the machine under ideal conditions. In equation form, that's:

W_in = W_out
F_effort x d_effort = F_resistance x d_resistance

In this problem, the effort work is 760 ft⋅lb and the resistance force is 190 lbs. and we need to calculate the resistance distance:

W_in = F_resistance x d_resistance
760 ft⋅lb = 190 lbs. x d_resistance
d_resistance = \( \frac{760ft⋅lb}{190 lbs.} \) = 4 ft.