Heat Temperature Effect of Heat -Thermal Expansion Types of Thermal Expansion -Phase Change

1. HEAT AND
TEMPERATURE

2. HEAT
--is the transfer of thermal energy from one
object to another because of a temperature
difference.
--exists as “energy in transit” or in the
process of being transferred and it is not
contained in an object.
--flows spontaneously from hot objects to
cold objects.

3. Why does heat
flow from a high to
a low
temperature?

4. Temperature
• It indicates the degree of hotness or
coldness of a body or a place.
• It is related to the average kinetic
energy of the particles in an object
due to their random motions through
space.

5. THERMAL ENERGY
--The energy that is actually contained
in an object due to the motion of its
particles.
--depends on the mass, temperature,
and phase (solid, liquid, or gas) of an
object.

6. How thermal energy
varies with temperature?

8. THERMAL EXPANSION

9. Heat

10. WHAT HAPPENS WHEN
MOLECULES GET MORE
ENERGY?

11. Molecules move MORE
MORE ENERGY
MOLECULES
MOVE MORE
WHAT HAPPENS WHENMOLECULES MOVE
MORE?
Molecules spread out.
MORE ENERGY = EXPANSION

12. WHAT HAPPENS
WHEN MOLECULES
GET LESS ENERGY?

13. Molecules move LESS
LESS ENERGY
MOLECULES
MOVE LESS
WHAT HAPPENS WHENMOLECULES MOVE
LESS?
Get close together
LESS ENERGY = CONTRACTION

15. - Expansion is directly proportional to
temperature change.
• A solid expands when heated, contracts
when its temperature decreases.

19. PHASE CHANGE

20. PHASE CHANGE
Examples:
Water can change from solid (ice)
to liquid (water) or from gas (steam).
*The high temperature water
transferred more heat than water at a
lower temperature.
*A greater increase in temperature of
the object that absorbed the heat.

21. Some materials absorb heat
more readily than others.
When a car is heated by the
sun, the temperature of the
metal door increases more
than the temperature of the
plastic bumper. Do you know
why?

22. HEAT CAPACITY
• The amount of heat needed by a
material to increase its temperature
by a degree.
• Also known as SPECIFIC HEAT
CAPACITY(c), and this refers to the
amount of heat required to increase
the temperature of one unit mass of
given material by one Celsius degree.

23. Quantity of Heat
• Heat is measured in joules or calories
(cal).
CALORIE (cal) – is the energy needed to
raise the temperature of 1 gram of water by
1°C.
1 cal = 4.184 J
• Heat (Q) absorbed by a material equals the
product of the mass (m), the specific heat
(c), and the change in temperature ( T).
Q = mc T

24. SPECIFIC HEAT CAPACITY
MATERIALS SPECIFIC HEAT
Aluminum 0.215 cal/g°c
Copper 0.93 cal/g°c
Glass 0.20 cal/g°c
Ice 0.50 cal/g°c
Iron 0.11 cal/g°c
Wood 0.4 cal/g°c
Mercury 0.033 cal/g°c
Water 1.00 cal/g°c

25. The lower a material’s
specific heat, the more its
temperature increases when
heat is absorbed.

26. Thank you! 