ASVAB Mechanical Comprehension Practice Test 956306 Results

Your Results Global Average
Questions 5 5
Correct 0 3.14
Score 0% 63%

Review

1

The mechanical advantage of a wheel and axle is equal to the:

61% Answer Correctly

ratio of the diameters of the wheels

length of the axle

difference in the lengths of the axles

difference in the diameters of the wheels
Solution

A wheel and axle uses two different diameter wheels mounted to a connecting axle. Force is applied to the larger wheel and large movements of this wheel result in small movements in the smaller wheel. Because a larger movement distance is being translated to a smaller distance, force is increased with a mechanical advantage equal to the ratio of the diameters of the wheels. An example of a wheel and axle is the steering wheel of a car.

2

Drag is a type of:

83% Answer Correctly

kinetic energy

potential energy

work

friction
Solution

Drag is friction that opposes movement through a fluid like liquid or air. The amount of drag depends on the shape and speed of the object with slower objects experiencing less drag than faster objects and more aerodynamic objects experiencing less drag than those with a large leading surface area.

3

Lisa lifts a 25 pound box from the floor onto a loading dock 4 ft. off the ground. Sam slides the same box along a ramp to move it up another 4 ft. onto a flatbed truck. Who has done more work?

50% Answer Correctly

Sam

Lisa

Neither have done any work

They have done an equal amount of work
Solution

Work is force multiplied by distance. Because both Connie and Sam moved the same weight the same distance they have done an equal amount of work. Sam employed the mechnacial advantage of an inclined plane so he exerted less effort to do the work but the amount of work done was still the same.

4 How much work can a 7 hp engine do in 4 seconds?
53% Answer Correctly
1 ft⋅lb
0 ft⋅lb
15400 ft⋅lb
28 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:
\( W = 7 hp \times 550 \frac{ft⋅lb}{s} \times 4s = 15400 ft⋅lb \)
5 What is the efficiency of a machine has work input of 170 ft⋅lb and work output of 110 ft⋅lb?
68% Answer Correctly
16%
130%
260%
65%
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:
\( Efficiency = \frac{Work_{out}}{Work_{in}} \times 100 \) \( = \frac{110 ft⋅lb}{170 ft⋅lb} \times 100 \) \( = 65% \) %