ASVAB ASVAB Certifications ASVAB-SECTION-3 Questions & Answers

• Question 71:

  The amount of magnification that a machine produces is referred to as the __________.

  A. effort arm

  B. work

  C. mechanical advantage

  D. efficiency

  Correct Answer: C

  By using a machine, it is possible to multiply the amount of effort expended to get a job done. Mechanical advantage is the amount of magnification, or the ratio of load to effort.

• Question 72:

  The ratio between work output and work input is called __________.

  A. efficiency

  B. work

  C. leverage

  D. mass

  Correct Answer: A

  In order to find out how well work was performed and how much effort was expended in getting the job done, the term efficiency is used to describe the ratio of work input to work output.

• Question 73:

  Work input is always more than work output because of __________.

  A. gravity

  B. buoyancy

  C. friction

  D. tension

  Correct Answer: C

  Efficiency is affected by friction. It is a ratio of how much effort went into a job compared to what was produced or outputted. Therefore, work input is more than the work output. Friction accounts for the loss in efficiency.

• Question 74:

  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

  Correct Answer: B

  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 75:

  Which weight exerts more pull on the horizontal bar from which both weights hang by strings as shown?

  

  A. Block A

  B. Block B

  C. Both exert the same pull

  D. Insufficient information to solve this problem

  Correct Answer: A

  The string holding the 10-lb. weight exerts more pull on the bar. The fact that that string is longer does not change how much tension is on it due to the weight at its end.

• Question 76:

  A good example of a simple machine is a __________.

  A. manually operated pencil sharpener

  B. doorknob

  C. light switch

  D. all of the above

  Correct Answer: D

  Simple machines are devices that make work easier.

  Some examples of simple machines are levers, hydraulic jacks, loading ramps, vises, and machines that

  spin ?winches and gears. Door knobs, light switches, and manually operated pencil sharpeners are also

  simple machines.

• Question 77:

  

  In the figure, the angle b is important, since when it is __________.

  A. 0 degrees the entire force is dragging the box

  B. 90 degrees the entire force is lifting the box

  C. both lifting and dragging between 10 degrees and 90 degrees

  D. all of the above

  Correct Answer: D

  The angle of the rope determines if the box is being pulled along the floor or being lifted from the floor. That means it can be both lifted and pulled along at any angle that is more than 0 degrees and less than 90 degrees.

• Question 78:

  If an object is in equilibrium, it is said to be __________.

  A. at rest

  B. moving

  C. at rest or moving at a constant speed and in a straight line

  D. moving upward only

  Correct Answer: C

  An object in equilibrium may or may not be at rest. If two or more forces act, their effects may eliminate

  each other.

  When this condition of equilibrium is reached, there is no net force and the velocity does not change.

  Equilibrium is reached when the object is at rest or moving at a constant speed and in a straight line.

• Question 79:

  When the plug in the tube is removed, water will flow ___________.

  

  A. into the tube

  B. out of the tube

  C. neither direction

  D. impossible to tell

  Correct Answer: A

  When the plug is removed, water will flow into the tube to equalize the water level both inside and outside the tube.

• Question 80:

  In the illustration below, two 30-lbs blocks are attached to the ceiling using ropes, as shown.

  Which of the following statements is true?

  

  A. All the ropes are under equal amounts of tension.

  B. The rope supporting Block A is under 2x the tension of the ropes holding Block B.

  C. The ropes supporting Block B are under 1/3 of the tension of the rope holding Block A.

  D. The rope holding Block A is under 1/3 of the tension of the ropes holding Block B.

  Correct Answer: C

  There are three ropes supporting Block B; therefore, they are under 1/3 the tension as the rope supporting Block A.