ASVAB Mechanical Comprehension Practice Test 858634 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.26
Score	0%	65%

Review

The mass of an object correlates to the size of the object but ultimately depends on:

67% Answer Correctly

	gravity
	the object's weight
	the object's density
	the object's potential energy

Solution

Mass is a measure of the amount of matter in an object. In general, larger objects have larger mass than smaller objects but mass ultimately depends on how compact (dense) a substance is.

2 What is the efficiency of a machine has work input of 155 ft⋅lb and work output of 38 ft⋅lb?

67% Answer Correctly

	0%
	25%
	50%
	75%

Solution

Due to friction, a machine will never be able to utilize 100% of its work input. A certain percentage of that input will be lost in overcoming friction within the machine. Effeciency is a measure of how much of a machine's work input can be turned into useful work output and is calculated by dividing work output by work input and multiplying the result by 100:
\( Efficiency = \frac{Work_{out}}{Work_{in}} \times 100 \) \( = \frac{38 ft⋅lb}{155 ft⋅lb} \times 100 \) \( = 25% \) %

Hydraulics is the transmission of force through the use of which of the following?

74% Answer Correctly

	gear systems
	air pressure
	torque
	liquids

Solution

Hydraulics is the transmission of force through the use of liquids. Liquids are especially suited for transferring force in complex machines because they compress very little and can occupy very small spaces. Hydraulic pressure is calculated by dividing force by the area over which it is applied: P = F/A where F is force in pounds, A is area in square inches, and the resulting pressure is in pounds per square inch (psi).

The measure of how much of the power put into a machine is turned into movement or force is called:

56% Answer Correctly

	mechanical advantage
	efficiency
	force multiplication
	power

Solution

The efficiency of a machine describes how much of the power put into the machine is turned into movement or force. A 100% efficient machine would turn all of the input power into output movement or force. However, no machine is 100% efficient due to friction, heat, wear and other imperfections that consume input power without delivering any output.

Coplanar forces:

62% Answer Correctly

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

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.