ASVAB ASVAB-SECTION-3 Online Practice Questions and Exam Preparation

ASVAB ASVAB-SECTION-3 Online Questions & Answers

• Question 1:

  Which mechanical components are typically used between a wheel and an axle to reduce friction?

  A. springs
  B. hinges
  C. bearings
  D. levers
  C. bearings

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  A set of bearings is typically a set of small metal balls packed in a groove and lubricated with grease or oil. The wheel rubs against one side of each ball, and the axle rubs against the other side. The net effect is that the wheel rolls much more easily.

• Question 2:

  Wheel A has a diameter of 10 feet. Wheel B has a diameter of 8 feet.

  If both wheels revolve at the same rate, Wheel B will cover a linear distance of 16 feet ___________.

  A. at the same time as Wheel A
  B. more slowly than Wheel A
  C. in twice the time as Wheel A
  D. faster than Wheel A
  B. more slowly than Wheel A

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  Wheel B has to make more revolutions than Wheel A to cover the same amount of distance, so it will go slower.

• Question 3:

  The mechanical advantage of a winch is the ratio of the radius of the crank to the radius of the __________.

  A. arm
  B. lever
  C. fulcrum
  D. shaft
  D. shaft

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  The principle of a winch is not much different from that of a lever.

  Since the crank and the shaft turn together, the torque exerted by the effort (the force on the handle) must be equal to the torque exerted by the load (the tension in the rope). The mechanical advantage then is the ratio of the radius of the

  crank to the radius of the shaft.

• Question 4:

  For two gears to mesh properly, they must __________.

  A. rotate at the same speed
  B. rotate in the same direction
  C. have the same size teeth
  D. have the same number of teeth
  C. have the same size teeth

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  For two gears to mesh properly, they must have the same size teeth.

  Different size gears will, by definition, rotate at different speeds even when their driving axles are moving at the same speed.

  Also, interlocking or meshing gears rotate in opposite directions.

• Question 5:

  In the water system shown below, assume that the main tank starts empty and that all the valves are closed. In order for the tank to fill about halfway and keep that level, which valves have to be open?

  

  A. Valves A, B, and C
  B. Valves A, B, and D
  C. Valves A, E, and B
  D. Valves A, E, and C
  B. Valves A, B, and D

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  Valves A, B, and D must be open for the tank to fill halfway and maintain that level.

  Water flows in through Valve A (meaning that any choice not including Valve A is automatically incorrect), and flows out when the tank is half full through Valve B.

  However, for that water to leave the system Valve D must also be open.

• Question 6:

  A gear and pinion have a ratio of 4 to 1.

  If the gear makes 200 revolutions per minute, the speed of the pinion is __________.

  A. 50 rpm
  B. 800 rpm
  C. 400 rpm
  D. 200 rpm
  B. 800 rpm

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  The pinion turns 4 times as often as the gear: 4 × 200 = 800.

• Question 7:

  Which principle of mechanical motion is used in the design of a roller coaster?

  A. momentum
  B. friction
  C. acceleration
  D. all of the above
  D. all of the above

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  Acceleration must be considered in designing the maximum rise of the first hill.

  Momentum must be considered to ensure the train gets back to the starting point, since it has no motor.

  Friction must be considered in the design of the braking system.

• Question 8:

  If a water tank on a toilet keeps overflowing, the problem is probably a ___________.

  A. defective float
  B. clogged pipe
  C. crimped chain
  D. improper seal
  A. defective float

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  The float measures the water level in the tank. If the tank overflows, the float is probably defective.

• Question 9:

  

  In the figure shown above, the board holds the weight of the cat. The board is placed on two identical scales. Each scale reads ___________.

  A. 24
  B. 10
  C. 12
  D. 40
  C. 12

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  The 20-pound cat and the 4-pound board weigh 24 pounds total or, divided by 2, 12 pounds per scale.

• Question 10:

  A yellow flame on a gas furnace indicates __________.

  A. Everything is fine.
  B. The fuel-air mixture is too rich.
  C. The fuel-air mixture is too lean.
  D. The gas pressure is too low.
  B. The fuel-air mixture is too rich.

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  A yellow flame indicates too much fuel or not enough air. More air should be allowed to enter and mix with the gas. Thus, the fuel-air mixture is too rich.