Unit 202 - Scientific Principles within RAC and HP Systems

Which of the following is the base unit of length used in the SI system of measurement ?

• Millimetre

• Centimetre

• Metre

• Kilometre

When using the SI system of measurement, which temperature scale must be used?

• Baume

• Kelvin

• Rankine

• Celsius

Which of the following is the speed at which molecules move about in a substance ?

• Temperature

• Internal Energy

• Enthalpy

• Entropy

Zero degrees on the celsius temperature scale was established by using which of the following values as a reference point ?

• Fusion point of mercury at atmospheric pressure

• Boiling point of water at 300 microns

• Vaporisation point of mercury at 3000 microns

• Melting point of ice at atmospheric pressure

The temperature known as absolute zero is...

• The temperature used for organic food storage

• 300 degrees below the melting point of ice

• the lowest possible temperature that can be attained

• created when gas molecules approach the speed of light

Answer explanation

Boomerang Nebula: The rapid expansion of gases resulting in the Boomerang Nebula causes the lowest observed temperature outside a laboratory.

The temperature of 200k has which of the following values when converted to Celsius ?

• Minus 73°c

• Minus 50°c

• Minus 30°c

• Minus 10°c

Which of the following describes the second law of thermodynamics ?

• Heat and work are interchangeable

• When work is done on a substance, heat is produced

• Heat Flows from hot to cold

• evaporator temperatures must be lower than air temperatures

Overheating in an unlubricated fan bearing is an application of which of the thermodynamic law ?

• Boyles law

• Charles law

• First Law

• Second Law

in order that heat energy can transfer between 2 bodies, which of the following conditions is necessary ?

• there must be a temperature difference between the bodies

• the bodies must be in contact

• the bodies must be apart

• there must be a pressure difference between the bodies

Heat transfer by convection can only take place...

• Between two gases

• between solids and liquids

• in liquids and gases

• in a vacuum