ASVAB Mechanical Comprehension Practice Test 960850 Results

	Your Results	Global Average
Questions	5	5
Correct	0	3.32
Score	0%	66%

Review

1 What is the efficiency of a machine has work input of 180 ft⋅lb and work output of 144 ft⋅lb?

67% Answer Correctly

	160%
	320%
	80%
	40%

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:
\( Efficiency = \frac{Work_{out}}{Work_{in}} \times 100 \) \( = \frac{144 ft⋅lb}{180 ft⋅lb} \times 100 \) \( = 80% \) %

2 If the radius of the axle is 5 and the radius of the wheel is 6, what is the mechanical advantage of this wheel and axle configuration?

52% Answer Correctly

	0.83
	-1
	6
	1.2

Solution

The mechanical advantage of a wheel and axle is the input radius divided by the output radius:

MA = \( \frac{r_i}{r_o} \)

In this case, the input radius (where the effort force is being applied) is 6 and the output radius (where the resistance is being applied) is 5 for a mechanical advantage of \( \frac{6}{5} \) = 1.2

The science that deals with motion and the forces that produce motion is called which of the following?

57% Answer Correctly

	mechanics
	physics
	engineering
	aeronautics

Solution

Mechanics deals with motion and the forces that produce motion.

On Earth, acceleration due to gravity (g) is approximately __________.

81% Answer Correctly

	9.8 m/s²
	1 m/s²
	1 m/s
	6.67 x 10^-11 m/s²

Solution

Newton's Law of Univeral Gravitation defines the general formula for the attraction of gravity between two objects: \(\vec{F_{g}} = { Gm_{1}m_{2} \over r^2}\) . In the specific case of an object falling toward Earth, the acceleration due to gravity (g) is approximately 9.8 m/s².

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

70% Answer Correctly

	mass
	potential energy
	weight
	density

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.