AMTS Fall Final Review- Physics (Rod's)

If a double-acting actuating cylinder in a 3,000 psi hydraulic system has a piston with a surface area of 3 in² on the extension side, & a rod with a cross-section area of 1 in² attached to the piston on the other side, approximately how much force will the actuator be able to produce when retracting?

• A- 9,000 pounds.

• B- 6,000 pounds.

• C- 3,000 pounds.

Answer explanation

Think Pascal’s Law(triangle): whenever you are finding area, force or pressure of a hydraulic system 

                               

The force a hydraulic actuator can exert is determined by the effective area of the piston & the pressure of the fluid acting on the piston.

The effective area on the retracting side of the piston is 2 in² …  

     effective area = (extension side - other side)

        2 in² x 3,000 psi = 6,000 pounds of force

The boiling point of a given liquid varies

• A- directly with pressure.

• B- inversely with pressure.

• C- directly with density.

Which of the following is NOT considered a method of heat transfer?

• Convection.

• Conduction.

• Diffusion.

• Radiation

Which condition is the actual amount of water vapor in a mixture of air and water?

• Relative humidity.

• Dewpoint.

• Absolute humidity.

Which is the ratio of the water vapor actually present in the atmosphere to the amount that would be present, if the air were saturated at the prevailing temperature and pressure?

• A- Absolute humidity.

• B- Relative humidity.

• C- Dewpoint.

The speed of sound in the atmosphere is most affected by...

• variations in the frequency of the sound.

• changes in

  temperature.

• changes in

  pressure.

Answer explanation

Air molecules have more energy at higher temperatures, which means they vibrate faster.

If the temperature of a confined liquid is held constant & its pressure is tripled, the volume will...

• triple

• be reduced to one-third its original volume.

• remain the same.

Answer explanation

**Liquids are incompressible. So, if the pressure is

tripled the volume will not change...

*as long as temperature stays constant

-increasing the temperature will change some of the liquid to gas & gases are compressible

Which atmospheric conditions will cause the true landing speed of an aircraft to be the greatest?

• A- Low temperature with low humidity.

• B- High temperature with low humidity.

• C- High temperature with high humidity.

1. If both the volume & the temperature of a confined gas are doubled, the pressure will...

• not change

• be halved

• become 4 times as great

Answer explanation

**when dealing with gases:

>pressure is directly proportional to temperature

>pressure is inversely proportional to its volume

**So, if volume is doubled & temperature is doubled, they cancel each other out... the pressure will not change

According to Bernoulli's Principle, an airplane wing (as an airfoil) is designed to produce lift from

• positive (high) air pressure

  below & above

  the wing's surface along with the downward deflection of air.

• positive(high) air pressure below

  the wing's surface &

  negative(low) air pressure above

  the wing's surface along with the downward deflection of air.

• negative(low) air pressure below the wing's surface &

  positive(high) air pressure above

  the wing's surface along with the downward deflection of air.