PHYSICS HEAT & THERMODYNAMICS
EXAM QUESTIONS WITH CORRECT
ANSWERS
Will the numerical change between the initial and the final temperatures of something
be different if measured in Celsius or Kelvin? - ANSWER-No. The temperatures are
different, but the *change* is the same because a Celsius unit is the same size as a
Kelvin unit.
What is a *calorie*? - ANSWER-A unit of energy. One calorie is the energy needed to
raise the temperature of 1 gram of water by 1 degree.
What is a *joule*? - ANSWER-The standard unit of energy.
What is the conversion between a calorie and a joule? - ANSWER-1 calorie = 4.18
joules
Does a substance generally expand or contract when it is heated? - ANSWER-Expand.
What is *linear thermal expansion*? - ANSWER-The change in one dimension of a solid
when it's heated.
What is *volume thermal expansion*? - ANSWER-The change in a solid's volume when
it's heated.
During thermal expansion of a solid, both the change in length (∆l) and the change in
volume (∆V) are proportional to which 2 variable quantities? - ANSWER-The original
size (length or volume) and the change in temperature.
What are 3 ways in which heat is transferred? - ANSWER-1. conduction
2. convection
3. radiation
What is *conduction*? - ANSWER-Direct heat transfer through a material, whether it's
within the same material or between 2 materials that are in contact with each other.
What is *convection*? - ANSWER-Heat transfer by the movement of a fluid (liquid or
gas).
What is *radiation*? - ANSWER-Heat transfer by electromagnetic waves.
Do warmer fluids (liquids or gases) sink or rise? - ANSWER-Rise.
, Do cooler fluids (liquids or gases) sink or rise? - ANSWER-Sink.
One end of a metal rod is heated until the other end warms up. Is this an example of
conduction, convection, or radiation? - ANSWER-Conduction. Direct heat transfer within
a material (metal rod).
You burn your hand by accidentally touching a hot pan. Is this an example of
conduction, convection, or radiation? - ANSWER-Conduction. Direct heat transfer by
the contact of 2 materials (pan and skin).
A space heater warms up a room as warmer air rises and cooler air sinks. Is this an
example of conduction, convection, or radiation? - ANSWER-Convection. Heat transfer
by fluid (air) movement.
Water is heated in a pot as warmer water rises and cooler water sinks. Is this an
example of conduction, convection, or radiation? - ANSWER-Convection. Heat transfer
by fluid (water) movement.
The sum warms the earth. Is this an example of conduction, convection, or radiation? -
ANSWER-Radiation. Sun transfers heat through electromagnetic waves (like visible
light, infrared, and ultraviolet).
A microwave heats food. Is this an example of conduction, convection, or radiation? -
ANSWER-Radiation. Microwaves are electromagnetic waves.
A flat piece of metal with a hole in it is heated. Does the hole get bigger or smaller? -
ANSWER-Bigger. Everything gets bigger during thermal expansion, even the
dimensions of a hole, because if the hole had been filled with the some other material,
then that piece would've gotten bigger.
Why do warmer fluids rise? - ANSWER-Because substances expand (take up more
volume) as they're heated. But the mass stays constant, so the same mass with a
bigger volume results in a lower density (density = mass / volume). And lower density
things rise.
If you wanted to efficiently heat a 2-floor house, would it be better to put the heater on
the 1st floor or the 2nd floor? - ANSWER-The 1st floor because the warmer air would
rise to the 2nd floor. If you put the heater on the 2nd floor, the warmer air won't sink to
the 1st floor.
If you wanted to efficiently cool the inside of a refrigerator, would it be better to put the
cooling coil on the top or the bottom of the refrigerator? - ANSWER-The top because
the cooler air would sink to the bottom of the refrigerator. If you put the cooling coil on
the bottom, the cooler air won't rise to the top.
EXAM QUESTIONS WITH CORRECT
ANSWERS
Will the numerical change between the initial and the final temperatures of something
be different if measured in Celsius or Kelvin? - ANSWER-No. The temperatures are
different, but the *change* is the same because a Celsius unit is the same size as a
Kelvin unit.
What is a *calorie*? - ANSWER-A unit of energy. One calorie is the energy needed to
raise the temperature of 1 gram of water by 1 degree.
What is a *joule*? - ANSWER-The standard unit of energy.
What is the conversion between a calorie and a joule? - ANSWER-1 calorie = 4.18
joules
Does a substance generally expand or contract when it is heated? - ANSWER-Expand.
What is *linear thermal expansion*? - ANSWER-The change in one dimension of a solid
when it's heated.
What is *volume thermal expansion*? - ANSWER-The change in a solid's volume when
it's heated.
During thermal expansion of a solid, both the change in length (∆l) and the change in
volume (∆V) are proportional to which 2 variable quantities? - ANSWER-The original
size (length or volume) and the change in temperature.
What are 3 ways in which heat is transferred? - ANSWER-1. conduction
2. convection
3. radiation
What is *conduction*? - ANSWER-Direct heat transfer through a material, whether it's
within the same material or between 2 materials that are in contact with each other.
What is *convection*? - ANSWER-Heat transfer by the movement of a fluid (liquid or
gas).
What is *radiation*? - ANSWER-Heat transfer by electromagnetic waves.
Do warmer fluids (liquids or gases) sink or rise? - ANSWER-Rise.
, Do cooler fluids (liquids or gases) sink or rise? - ANSWER-Sink.
One end of a metal rod is heated until the other end warms up. Is this an example of
conduction, convection, or radiation? - ANSWER-Conduction. Direct heat transfer within
a material (metal rod).
You burn your hand by accidentally touching a hot pan. Is this an example of
conduction, convection, or radiation? - ANSWER-Conduction. Direct heat transfer by
the contact of 2 materials (pan and skin).
A space heater warms up a room as warmer air rises and cooler air sinks. Is this an
example of conduction, convection, or radiation? - ANSWER-Convection. Heat transfer
by fluid (air) movement.
Water is heated in a pot as warmer water rises and cooler water sinks. Is this an
example of conduction, convection, or radiation? - ANSWER-Convection. Heat transfer
by fluid (water) movement.
The sum warms the earth. Is this an example of conduction, convection, or radiation? -
ANSWER-Radiation. Sun transfers heat through electromagnetic waves (like visible
light, infrared, and ultraviolet).
A microwave heats food. Is this an example of conduction, convection, or radiation? -
ANSWER-Radiation. Microwaves are electromagnetic waves.
A flat piece of metal with a hole in it is heated. Does the hole get bigger or smaller? -
ANSWER-Bigger. Everything gets bigger during thermal expansion, even the
dimensions of a hole, because if the hole had been filled with the some other material,
then that piece would've gotten bigger.
Why do warmer fluids rise? - ANSWER-Because substances expand (take up more
volume) as they're heated. But the mass stays constant, so the same mass with a
bigger volume results in a lower density (density = mass / volume). And lower density
things rise.
If you wanted to efficiently heat a 2-floor house, would it be better to put the heater on
the 1st floor or the 2nd floor? - ANSWER-The 1st floor because the warmer air would
rise to the 2nd floor. If you put the heater on the 2nd floor, the warmer air won't sink to
the 1st floor.
If you wanted to efficiently cool the inside of a refrigerator, would it be better to put the
cooling coil on the top or the bottom of the refrigerator? - ANSWER-The top because
the cooler air would sink to the bottom of the refrigerator. If you put the cooling coil on
the bottom, the cooler air won't rise to the top.
