ASVAB Mechanical Comprehension Practice Test 352580 Results

Your Results Global Average
Questions 5 5
Correct 0 2.96
Score 0% 59%

Review

1

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

They have done an equal amount of work

Neither have done any work

Sam

Lisa
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.

2

A fixed pulley is useful for which of the following?

53% Answer Correctly

changing the direction of the input force

multiplying the input distance

multiplying the input force

changing the direction of the output force
Solution

A fixed pulley is used to change the direction of a force and does not multiply the force applied. As such, it has a mechanical advantage of one. The benefit of a fixed pulley is that it can allow the force to be applied at a more convenient angle, for example, pulling downward or horizontally to lift an object instead of upward.

3 The radius of the axle is 5, the radius of the wheel is 8, and the blue box weighs 85 lbs. What is the effort force necessary to balance the load?
53% Answer Correctly
5 lbs.
12.8 lbs.
53.13 lbs.
40 lbs.
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 8 and the output radius (where the resistance is being applied) is 5 for a mechanical advantage of \( \frac{8}{5} \) = 1.6

MA = \( \frac{load}{effort} \) so effort = \( \frac{load}{MA} \) = \( \frac{85 lbs.}{1.6} \) = 53.13 lbs.

4 50 lbs. of effort is used by a machine to lift a 300 lbs. box. What is the mechanical advantage of the machine?
84% Answer Correctly
6
6.6
5
18
Solution

Mechanical advantage is resistance force divided by effort force:

MA = \( \frac{F_r}{F_e} \) = \( \frac{300 lbs.}{50 lbs.} \) = 6

5

An inclined plane increases ___________ to reduce ____________.

58% Answer Correctly

distance, force

force, power

distance, power

force, distance
Solution

An inclined plane is a simple machine that reduces the force needed to raise an object to a certain height. Work equals force x distance and, by increasing the distance that the object travels, an inclined plane reduces the force necessary to raise it to a particular height. In this case, the mechanical advantage is to make the task easier. An example of an inclined plane is a ramp.