Answers
Thermal Energy and Heat
Unit 5 Study Guide
1. C
2. A
3. C
4. C
5. A
6. A
7. C
8. B
9. C
10. D
11. kinetic
12. Kelvin
13. thermal energy
14. silver
15. thermal expansion
16. F,100°C
17. T
18. F, convection
19. F, insulator
20. F, contract
21. Beaker C. The thermal energy of the
water increases with temperature and
with the number of molecules. Because
beaker C has the highest temperature
and as much water as any other beaker,
it has the most thermal energy.
22. Beakers A and B. Temperature is a
measure of the average kinetic energy
of the particles in a substance. Since
the water temperature is the same in
both beakers, the water molecules have
the same average kinetic energy.
23. A change in temperature of 1 Celsius
degree is greater than a temperature
change of 1 Fahrenheit degree because
a Celsius degree is larger than a
Fahrenheit degree. The Celsius degree
is larger because there are 100 Celsius
degrees between the freezing and boiling
points of water, but there are 180
Fahrenheit degrees between the same
points.
24. Thermal energy is the total energy of
all of the particles of a substance. Heat
is the movement of thermal energy from
a substance at a higher temperature to
another at a lower temperature.
Thermal energy is a form of energy,
while heat is the transfer of energy.
25. Air is a poor conductor of heat and
thus acts as an insulator. The air space
reduces the heat transfers by conduction.
26. Without an air layer, the single pane
allows heat to escape easily by
conduction.
27. As a fluid absorbs heat, it expands,
which causes its density to decrease. If
a fluid is heated from below, the
warmer, less-dense fluid rises and the
cooler, denser fluid sinks into its place.
This cooler fluid is warmed, becomes
less dense, and rises. The warmer, lessdense fluid transfers heat to the fluid
around it as it rises. As it transfers heat,
it cools, becomes denser, and sinks.
The continuous rising of warmed fluid
and the sinking of cooled fluid form
convection currents.
28. Conduction transfers energy within an
object or between objects when fastmoving particles collide with slowermoving particles and transfer kinetic
energy, making the slower particles
move faster.
Thermal Energy and Heat
Chapter Tests