4. Heat
is a form of energy being transferred
from a hot body to a cold body.
The
total amount of heat in a body depends
on the mass, material and temperature of
the body.
5. Temperature
is a measure of the degree of
hotness of a body.
A
hot body has a high temperature whereas
a cold body has a low temperature.
6. TEMPERATURE
HEAT
The degree of hotness of
a body
A form of energy
Base quantity
Derived quantity
Unit: kelvin (K) or degree
celcius (oC)
Unit : joule (J)
Can be measured using
the thermometer.
No specific measuring
equipment.
7. 4.1:
UNDERSTANDING THERMAL EQUILIBRIUM
Thermal
equilibrium
Liquid in glass thermometer
4.2:
UNDERSTANDING SPECIFIC HEAT CAPACITY
Specific
heat capacity
Applications
4.3:
UNDERSTANDING SPECIFIC LATENT HEAT
4.4: UNDERSTANDING THE GAS LAWS
Boyle’s
Charles’
Pressure
8. Which
has a higher temperature ?
: A steaming cup of tea or a huge
iceberg?
The answer is obvious -- the tea
is at a higher temperature.
But which of the two has more
heat?
9. The total amount
.
of heat in a body
depends on the
mass, material
and temperature
of the body
10.
11. Energy is transferred
at a faster rate from
the hotter object # 1
to the cooler object
#2.
Energy is transferred
at a slower rate from
the cooler object # 2
to the hotter object #
1.
The hot object loses energy while the cold object
gains energy.
12. This causes the hot
object to cool down
while the cold object
warms up.
After some time, the
rates of energy transfer
between the two
objects become equal.
The two objects in thermal equilibrium have
the same temperature
13. After some time, the rates of energy transfer between
the two objects become equal.
energy
There is no net heat transfer between the two
objects. The two objects are said to be in
Thermal equilibrium.
14. When raw food, e.g. meat
is put in the oven, heat
from the oven is transferred
to it.
This process will continue
until thermal equilibrium is
reached between the food
and the oven.
Electric oven /
microwave oven
The temperature of the
food and the oven will be
the same when the food is
cooked.
15. When food are kept in the
refrigerator, the heat from
the food is released to the
cold air in the fridge.
This process continues until
thermal equilibrium is
reached between the food
and the fridge.
The temperature of the food
will be equal to the
temperature of the fridge.
refrigerator
Hence the food are maintained in good condition
16. The thermometer is placed below
the
tongue,
so
that
the
thermometer is in contact with the
mouth and tongue of the patient.
Heat will flow from the patient’s
tongue to the bulb of the
thermometer
After about a minute, thermal
equilibrium is reached between
the
thermometer
and
the
patient’s tongue/body.
Taking the temperature of a sick
person
Therefore,
the
temperature
reading
shows
the
body
temperature of the patient.
19. Heat
will flow from the tongue
to the bulb ,and this process
will continue until TE is
reached.
The thermometer reading
shows the body temperature.
20. Same volume of
water at different
temperatures.
27oC
100oC
The water which is at
higher temperature has
a greater quantity of
heat compared with
the water which is at a
lower temperature.
21. HOT WATER
glass
jug
Hot water in both the glass and the jug.
The water in the jug is hotter to touch compared to the water
in the glass.
The water in the jug has a greater quantity of heat compared
to the water in the glass, because the water in the jug has a
greater mass.
22. Iron plate
Mica plate
An iron plate and a mica plate of the same mass are put into the oven.
After half a minute , the iron plate has a greater increase in temperature
compared to the mica plate.
This shows that heat absorbed is dependent on the type of materials.
23. 2
factors affecting heat capacities…
i) ________________________
ii) ________________________
Specific
Heat capacity: the amount of heat required to
increase the temperature of 1 kg of a substance by 10C.
24. Amount
of heat , q (joule)
MASS, m (KILOGRAM)
CHANGE IN TEMPERATURE, Дθ (0C )
SPECIFIC HEAT CAPACITY, c
c =
Q___
m Δθ
Unit : J kg-1 0C-1
25. The sparks of a sparkler do not
burn the hand of a person.
However if the person touches the
glowing part of the sparkler,
he/she will get burn.
sparkler
This because the sparks have a
smaller amount of heat compared
to the glowing sparkler
26. A bowl of vegetable soup is too
hot to drink.
However, the vegetable in the
soup can be eaten slowly
although the soup and the
vegetables are of the same
temperature.
A bowl of vegetable
soup
Why?
