To study the relationship between the temperature of a hot body and its time of cooling by plotting a cooling curve.
Theory
This Law of Cooling is named after the famous English Physicist Sir Isaac Newton, who conducted the first experiments on the nature of cooling.
Statement of the Law :
According to Newton’s Law of Cooling, the rate of cooling of a body is directly proportional to the difference in temperatures of the body (T) and the surrounding (T0), provided difference in temperature should not exceed by 300C.
From the above statement,
For a body of mass m, specific heat s, and temperature T kept in surrounding of temperature T0;
Now, the rate of cooling,
Hence ,
Since the mass and the specific heat of the body are taken as constants, the rate of change of temperature with time can be written as,
The above equation explains that, as the time increases, the difference in temperatures of the body and surroundings decreases and hence, the rate of fall of temperature also decreases.
It can be graphically represented as,
Learning Outcomes
Materials Required:
Real Lab Procedure:
Simulator Procedure (as performed through the Online Labs):
Observations:
Sl. No. | Time for cooling, t (mt.) | Temperature of water in calorimeter, T(oC) | Temperature of water in enclosure, T0 (oC) | Difference of temperature, (T-T0) (oC) |
1 | 0 | 70 | ||
2 | 1 | |||
3 | 2 | |||
4 | 3 | |||
5 | 4 | |||
6 | 5 | |||
7 | 6 | |||
8 | 7 | |||
9 | 8 |
Calculations:
Results:
The cooling curve of the liquid is plotted.
The temperature falls quickly in the beginning and then slowly as the difference of temperature goes on decreasing.
This is in agreement with Newton’s Law of cooling.
26 videos|287 docs|64 tests
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1. What is Newton's law of cooling? |
2. How can Newton's law of cooling be applied in practical situations? |
3. What is the procedure to calculate the temperature of an object using Newton's law of cooling? |
4. Can Newton's law of cooling be used for objects undergoing phase changes? |
5. How does Newton's law of cooling relate to the concept of thermal equilibrium? |
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