ASVAB Mechanical Comprehension Practice Test 991282 Results

	Your Results	Global Average
Questions	5	5
Correct	0	2.61
Score	0%	52%

Review

1 How much work can a 8 hp engine do in 6 seconds?

52% Answer Correctly

	26400 ft⋅lb
	32 ft⋅lb
	1 ft⋅lb
	4 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:
\( W = 8 hp \times 550 \frac{ft⋅lb}{s} \times 6s = 26400 ft⋅lb \)

2 A mass of air has a pressure of 6.0 psi and a volume of 30 ft.³. If the air is compressed to a new volume of 20 ft.³, what is the new pressure?

56% Answer Correctly

	18 psi
	4.5 psi
	3 psi
	9 psi

Solution

According to Boyle's Law, pressure and volume are inversely proportional:

\( \frac{P_1}{P_2} \) = \( \frac{V_2}{V_1} \)

In this problem, V₂ = 20 ft.³, V₁ = 30 ft.³ and P₁ = 6.0 psi. Solving for P₂:

P₂ = \( \frac{P_1}{\frac{V_2}{V_1}} \) = \( \frac{6.0 psi}{\frac{20 ft.^3}{30 ft.^3}} \) = 9 psi

The principle of moments defines equilibrium in terms of:

54% Answer Correctly

	speed
	energy
	power
	torque

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.

A shovel is an example of which class of lever?

57% Answer Correctly

	third
	a shovel is not a lever
	second
	first

Solution

A third-class lever is used to increase distance traveled by an object in the same direction as the force applied. The fulcrum is at one end of the lever, the object at the other, and the force is applied between them. This lever does not impart a mechanical advantage as the effort force must be greater than the load but does impart extra speed to the load. Examples of third-class levers are shovels and tweezers.

Force of friction due to kinetic friction is __________ the force of friction due to static friction.

40% Answer Correctly

	lower than
	opposite
	the same as
	higher than

Solution

The formula for force of friction (F_f) is the same whether kinetic or static friction applies: F_{f =}μF_N. To distinguish between kinetic and static friction, μ_k and μ_s are often used in place of μ.