Free ASVAB Section 3: Mechanical Comprehension Exam Braindumps (page: 3)

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Air weighs about 15 psi.
What’s the amount of pressure (force) exerted on the top of your head, given a surface area of 24 inches?

  1. 360 pounds
  2. 625 pounds
  3. 5⁄8 pound
  4. 180 pounds

Answer(s): A

Explanation:

Power equals force divided by area in square inches (P = F⁄A). This formula can also be stated as F = A × P.
Substitute the known quantities.
F = 15 × 24 = 360 pounds.



The force produced when a boxer’s hand hits a heavy bag and “bounces” off it is called ________.

  1. static electricity
  2. magnetism
  3. recoil
  4. gravity

Answer(s): C

Explanation:

Recoil occurs when an object producing a force is kicked back.



In the figure above, if Gear 1 has 25 teeth and Gear 2 has 15 teeth, how many revolutions does Gear 2 make for every 10 revolutions Gear 1 makes?

  1. about 162/3
  2. 12
  3. about 1⁄3 more
  4. about 20

Answer(s): A

Explanation:

To determine the answer, multiply the number of teeth Gear 1 has D and the number of revolutions it makes (R).
Divide that number by the number of teeth Gear 2 has D to determine the number of revolutions Gear 2 makes (r).
Because the gears are proportional, this formula will show you the ratio of teeth to revolutions.
r = DR/d
r = (25 × 10)/15
r = 250⁄15, or 1610⁄15, or 162/3



A cubic foot of water weighs about 62.5 pounds.
If an aquarium is 18 feet long, 10 feet deep, and 12 feet wide, what’s the approximate pounds-per-square-inch pressure (psi) on the bottom of the tank?

  1. 2 psi
  2. 4 psi
  3. 5 psi
  4. 7 psi

Answer(s): B

Explanation:

You can determine the pressure of all that water by multiplying the volume of the aquarium by the weight of the water. Volume = lwh.
The bottom of the tank is 18 feet long by 12 feet wide by 10 feet high for a total volume of 2,160 cubic feet (18× 12 × 10).
A cubic foot of water weighs approximately 62.5 pounds.
2,160 × 62.5 gives an approximate pressure on the bottom of the tank of about 135,000 pounds over the entire surface area.
The surface area of the bottom of the tank is length × width. 216 inches (18 feet × 12) × 144 inches (12 feet × 12) = 31,104.
Dividing the pressure of 135,000 by the number of square inches of surface area gives an approximate PSI of 4.






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