Physics 011
A of
PQ#14A
Chapter 14: Heat
Practice
Questions


1. 

Which of
the following is a unit for Internal Energy? 


2. 

Which of
the following is an English unit for heat? 


3. 

The unit
of emissivity is Emissivity is unitless. Review Section 149 in Giancoli. 


4. 

The unit
for heat conduction would be a Review Section 147 in Giancoli. 


5. 

The unit
for radiant heat transfer is Review Section 149 in Giancoli. 


6. 

A
spaceship is drifting in an environment where the acceleration of gravity is
essentially zero. As the air on one side of the cabin is heated by an
electric heater, what is true about the convection currents caused by this
heating? 


7. 

In a
liquid at a given temperature, the molecules are moving in every direction,
some fast, some slowly. Electrical forces of adhesion tend to hold them
together. However, occasionally one molecule gains enough energy (as a result
of collisions) so that it pulls loose from its neighbors and escapes from the
liquid. Which of the following can best be understood in terms of this
phenomena? The process is known as evaporation. Review Section 146 in Giancoli. 


8. 

Radiant
energy is proportional to 


9. 

Conduction
is proportional to Actually, temperature difference. Review Section 147 in Giancoli. 


10. 

Conduction
is inversely proportional to This is connected to radiation. Review Section 147 in Giancoli. 


11. 

If the
thickness of a brick is 8 cm and its conductivity is 0.8J/s*m*C^{o}.
What is its thermal resistance? Review Section 147 in Giancoli. 


12. 

If a
wooden wall is 8 cm thick and has a conductivity of .08 J/s*m*C^{o},
what is its thermal resistance? Do not multiply. Review Section 147 in Giancoli. 


13. 

If a wall
is composed of 8 cm of wood and 8 cm of brick, what would be its total
thermal resistance? Thermal Resistances add. Review Section 147 in Giancoli. 


14. 

A piece of
hot metal is put into an equal mass of water. The water temperature rises 5
degrees and the metal's temperature drops 10 degrees. What is the specific
heat of the metal? Review Section 145 in Giancoli. 


15. 

The
specific heat of glass is 0.2 kcal/kg. If you put 1 kg of glass in contact
with an equal mass of water and its temperature drops 5 degrees, by how much will
the temperature of the water rise? 


16. 

How much
heat is needed to boil 1 kg of water to steam? 


17. 

How much
heat does it take to melt 1 kg of ice into water? 


18. 

In the
formula U=(3/2)nRT what is n? Review Section 143 in Giancoli. 


19. 

In the
formula U=(3/2)NkT what is N? Review Section 143 in Giancoli. 


20. 

What is
the internal energy (to the nearest joule) of 10 moles of Helium at 100 K? 


21. 

What is
the internal energy (to the nearest joule) of 10 moles of Oxygen at 100 K? Oxygen is a diatomic gas the formula applies only to monatomic gasses. 


22. 

On a clear
day at the equator with the sun directly overhead, how long would it take to
warm 10 kg of water 15 C^{o} if the emissivity of the 1.0 m ^{2}
surface is 1? 


23. 

On a very
clear dry dark night, little radiation is received from the sky. How much
energy, in one hour, will a perfectly black object, with 2 m^{2} of
surface area exposed only to the sky, radiate if its temperature is 50 ^{o}C
? 


24. 

Air is a
better insulator than fiberglass, yet we fill the air spaces in our walls
with fiberglass insulation. Why do we do this? 


25. 

Can you
take a picture of a perfectly black dog? A perfectly black surface will reflect no light. A camera works on reflected light. Unexposed areas of the film will be black upon developing. What you are left with is a picture of everything but the dog. Review Section 149 in Giancoli. 