1. Energy transfer
by heating
Temperature, Heat and Internal Energy

2. Relation between them Water Heat Temperature Transfer E Change T
Mass m
Temperature, Heat and Internal Energy

3. Relation?? Heat Transfer E : As E = P t, time for Heating indicates
how much energy is transferred.
Temperature Change T
Directly recorded from a thermometer
Mass m
By triple beam balance
Temperature, Heat and Internal Energy

4. E (proportional to time of heating) / min 1 2 3 4 5 61 2 3 4 5 6
T / oC
20.0
31.4
42.9
54.3
65.7
77.1
88.6
T / oC
11.4
22.9
34.3
45.7
57.1
68.6 E
 T
E  T
for fixed same mass m
Temperature, Heat and Internal Energy

5. for fixed same temp increase T
Mass of water / kg
0.25
0./75
1.0
Energy transfer E /s 53
104
155
211 E m
E  m
for fixed same temp increase T
Temperature, Heat and Internal Energy

6. for fixed same temp increase T
for fixed same mass m
E  m T
E  m
for fixed same temp increase T
E = c m T where c is a proportional constant
Specific heat capacity
c = E / m T
c = 1J kg-1 oC-1 or 1 J kg-1 K-1 certain material
means energy needed to increased the temperature
of 1kg the material by 1 oC is 1 J.
Temperature, Heat and Internal Energy

7. Specific heat capacity
Depends on the nature of material
Substance
Specific heat capacity / J kg-1 oC-1
water
4200
Alcohol
2500
Aluminium
900
Glass
600
Iron
480
Copper
370
Mercury
140
Temperature, Heat and Internal Energy

8. C = E / T heat capacity 1. Unit : J oC-1 or J K-1 2. C = mc
Same specific heat capacity
But different heat capacity
Temperature, Heat and Internal Energy

9. Specific heat capacity
Pg. 170, Qn (1 – 6)
Temperature, Heat and Internal Energy

10. Measurement of s.h.c. of water E = m c T
* Design of experiment and Setup
E = m c T
Temperature, Heat and Internal Energy

11. Measurement of s.h.c. of water * Design of experiment and Setup
* Data and Data Analysis
* Precautions
For safety measure:
Do not switch on the heater unless it is immersed
in water.
Temperature, Heat and Internal Energy

12. * Precautions Avoid energy lost to the surrounding by
(a) totally immersing the heater in the water,
(b) using polystyrene cup,
(c) using thermometer, stirrer, heater
and container of small s.h.c.
Ensure correct temperature is recorded by
(a) taking readings while a maximum attained
(b) stirring the water to have uniform temp.
The mass is correctly recorded by
* using a lid to prevent water from getting out.
Temperature, Heat and Internal Energy

13. Measurement of s.h.c. of aluminium E = m c T
* Design of experiment and Setup
E = m c T
Temperature, Heat and Internal Energy

14. Measurement of s.h.c. of aluminium * Design of experiment and Setup
* Data and Data Analysis
* Precautions
For safety measure:
Do not switch on the heater unless it is immersed
in water.
Temperature, Heat and Internal Energy

15. * Precautions Avoid energy lost to the surrounding by
(a) adding a few drop of oil to the holes
in the Al block to ensure good contact,
(b) placing the block on a polystyrene title,
Ensure correct temperature is recorded by
* taking readings while a maximum attained
Temperature, Heat and Internal Energy

16. Mesaurement of s.h.c. Improvements ?
Temperature, Heat and Internal Energy

17. mixtures A B High temp Low temp Energy lost in A = Energy gain in B
If there is no energy loss
Temperature, Heat and Internal Energy

18. Example of mixture A A B B Energy lost by hot water = mc T
0.4 kg
80oC
0.3 kg
10oC A B A B
Energy lost by hot water
= mc T
= (0.4)(4200)(80 – T)
T??
Energy lost by cold water
= (0.3)(4200)(T - 10)
(0.4)(4200)(80 – T) = (0.3)(4200)(T - 10)
T = 50oC
Temperature, Heat and Internal Energy

19. High s.h.c. of water Good Coolant
Temperature, Heat and Internal Energy

20. High s.h.c. of water Cooler in summer and milder in winter
Temperature, Heat and Internal Energy

21. High s.h.c. of water Watery fluid in human body
Temperature, Heat and Internal Energy