temperature, heat and internal energy energy transfer by heating
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Temperature, Heat and Internal Energy
Energy transfer by heating
Temperature, Heat and Internal Energy
Relation between them
Water
Mass m
HeatTransfer E
TemperatureChange T
Temperature, Heat and Internal Energy
Relation??
Mass mBy triple beam balance
Heat Transfer E : As E = P t, time for Heating indicates how much energy is transferred.
Temperature Change TDirectly recorded from a thermometer
Temperature, Heat and Internal Energy
E (proportional to time of heating) / min
0 1 2 3 4 5 6
T / oC 20.0 31.4 42.9 54.3 65.7 77.1 88.6
T / oC 0 11.4 22.9 34.3 45.7 57.1 68.6
E T for fixed same mass m
E
T
Temperature, Heat and Internal Energy
Mass of water / kg
0.25 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
E T for fixed same mass m
E m for fixed same temp increase T
E m 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 temperatureof 1kg the material by 1 oC is 1 J.
Temperature, Heat and Internal Energy
Specific heat capacityDepends 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
heat capacity
1. Unit : J oC-1 or J K-1
2. C = mc
Same specific heat capacity
But different heat capacity
C = E / T
Temperature, Heat and Internal Energy
Specific heat capacity
Pg. 170, Qn (1 – 6)
Temperature, Heat and Internal Energy
Measurement of s.h.c. of water
* Design of experiment and Setup
E = m c T
Temperature, Heat and Internal Energy
Measurement of s.h.c. of water
* Design of experiment and Setup
* Precautions
* Data and Data Analysis
For safety measure:Do not switch on the heater unless it is immersed in water.
Temperature, Heat and Internal Energy
* Precautions1. 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.
2. Ensure correct temperature is recorded by (a) taking readings while a maximum attained (b) stirring the water to have uniform temp.
3. The mass is correctly recorded by * using a lid to prevent water from getting out.
Temperature, Heat and Internal Energy
Measurement of s.h.c. of aluminium
* Design of experiment and Setup
E = m c T
Temperature, Heat and Internal Energy
Measurement of s.h.c. of aluminium
* Design of experiment and Setup
* Precautions
* Data and Data Analysis
For safety measure:Do not switch on the heater unless it is immersed in water.
Temperature, Heat and Internal Energy
* Precautions
1. 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
Mesaurement of s.h.c.
Improvements ?
Temperature, Heat and Internal Energy
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
Example of mixture
T??
Energy lost by hot water= mc T= (0.4)(4200)(80 – T)
Energy lost by cold water= (0.3)(4200)(T - 10)
A B A B0.4 kg80oC
0.3 kg10oC
(0.4)(4200)(80 – T) = (0.3)(4200)(T - 10)
T = 50oC
Temperature, Heat and Internal Energy
High s.h.c. of water
Good Coolant
Temperature, Heat and Internal Energy
High s.h.c. of water
Cooler in summer and milder in winter
Temperature, Heat and Internal Energy
High s.h.c. of water
Watery fluid in human body
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