ASVAB Mechanical Comprehension Practice Test 676677 Results

Your Results Global Average
Questions 5 5
Correct 0 3.50
Score 0% 70%

Review

1

Which of these is the formula for force?

77% Answer Correctly

F = a/m

F = am2

F = m/a

F = ma


Solution

Newton's Second Law of Motion states that "The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object." This Law describes the linear relationship between mass and acceleration when it comes to force and leads to the formula F = ma or force equals mass multiplied by rate of acceleration.


2

Which of the following will increase the mechanical advantage of this inclined plane?

59% Answer Correctly

shorten the ramp

increase the force acting at the blue arrow

lengthen the ramp

lower the force acting at the blue arrow


Solution

The mechanical advantage (MA) of an inclined plane is the effort distance divided by the resistance distance. In order to increase mechanical advantage, this ratio must increase which means making the effort distance longer and this can be accomplished by lengthening the length of the ramp.


3

A watt is the unit for which of the following?

71% Answer Correctly

mechanical advantage

work

power

energy


Solution

Power is the rate at which work is done, P = w/t, or work per unit time. The watt (W) is the unit for power and is equal to 1 joule (or newton-meter) per second. Horsepower (hp) is another familiar unit of power used primarily for rating internal combustion engines. 1 hp equals 746 watts.


4

The mechanical advantage of connected gears is proportional to which characteristic of the gears?

73% Answer Correctly

speed

diameter

number of teeth

circumference


Solution

The mechanical advantage (amount of change in speed or torque) of connected gears is proportional to the number of teeth each gear has. Called gear ratio, it's the ratio of the number of teeth on the larger gear to the number of teeth on the smaller gear.  For example, a gear with 12 teeth connected to a gear with 9 teeth would have a gear ratio of 4:3.


5 What is the efficiency of a machine has work input of 80 ft⋅lb and work output of 48 ft⋅lb?
67% Answer Correctly
40%
30%
1%
60%

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:
\( Efficiency = \frac{Work_{out}}{Work_{in}} \times 100 \) \( = \frac{48 ft⋅lb}{80 ft⋅lb} \times 100 \) \( = 60% \) %