ASVAB Mechanical Comprehension Practice Test 386759 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.16
Score	0%	63%

Review

Coplanar forces:

61% Answer Correctly

	act in a common plane
	pass through a common point
	have opposite dimensions
	act along the same line of action

Solution

Collinear forces act along the same line of action, concurrent forces pass through a common point and coplanar forces act in a common plane.

2 If the green arrow in this diagram represents 680 ft⋅lb of work, how far will the box move if it weighs 170 pounds?

72% Answer Correctly

	4 ft.
	85 ft.
	0 ft.
	2 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 680 ft⋅lb and the resistance force is 170 lbs. and we need to calculate the resistance distance:

W_in = F_resistance x d_resistance
680 ft⋅lb = 170 lbs. x d_resistance
d_resistance = \( \frac{680ft⋅lb}{170 lbs.} \) = 4 ft.

The force exerted on an object due to gravity is called:

70% Answer Correctly

	mass
	density
	potential energy
	weight

Solution

Mass is an intrinsic property of matter and does not vary. Weight is the force exerted on the mass of an object due to gravity and a specific case of Newton's Second Law of Motion. Replace force with weight and acceleration with acceleration due to gravity on Earth (g) and the result is the formula for weight: W = mg or, substituting for g, weight equals mass multiplied by 9.8 m/s².

Which of the following will increase the mechanical advantage of a second-class lever?

55% Answer Correctly

	decrease the length of the lever
	move the object being lifted closer to the fulcrum
	move the fulcrum between the force and the object being lifted
	move the object being lifted farther away from the fulcrum

Solution

A second-class lever is used to increase force on an object in the same direction as the force is applied. This lever requires a smaller force to lift a larger load but the force must be applied over a greater distance. The fulcrum is placed at one end of the lever and mechanical advantage increases as the object being lifted is moved closer to the fulcrum or the length of the lever is increased. An example of a second-class lever is a wheelbarrow.

Boyle's law defines the relationship between pressure and volume as:

57% Answer Correctly

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

Solution

Boyle's law states that "for a fixed amount of an ideal gas kept at a fixed temperature, pressure and volume are inversely proportional". Expressed as a formula, that's \(\frac{P_1}{P_2} = \frac{V_2}{V_1}\)