Question Where do we see heat transfer around us?
Learning objective -i Heat transfer
- Every time something heats or something cools down, it is due to heat transfer
- Whenever the temperature of any object increases or decreases, it is due to heat transfer
- When the temperature of an object increases (it becomes hotter), it means it is getting heat from somewhere
- When the temperature of an object decreases (it becomes colder), it means it is giving heat to something
learning objective-ii basic rule of heat transfer
- Heat always flows from high temperature(hotter things) to low temperature(cooler things)
Question HEAT TRANSFER IN ACTION
What is happening here?
Cold ice is transferring its coldness to the hand - Wrong X
Cold ice is transferring its coldness to the drink - Wrong X
QUESTION Why do we feel hot or cold?
Heat transfer from hand to ice
Heat transfer from cup to hands
question open windows
In winters, people often say- "Don't open the window, you will let the cold in".
Do you agree with this statement? If not, why?
Cold in X
Heat out
learning objective-ii basic rule of heat transfer
Heat always flows from high temperature(hotter ) to low temperature(cooler)
Question Hot or cold?
COLD
HOT
Question Hot or cold ?
HOT
COLD
Question Hot or cold?
HEAT FLOW
HOT
/COLD
HOT
COLD
Learning objective iii hot & cold are relative terms
- Whether something is hot or cold depends on what you are comparing it with
- A body at 60 degrees celcius will be hot to a body at 25 degrees celcius. But the same body will be cold compared to a body at 100 degrees celcius
Experiment DO AT HOME
37 degrees celcius
NORMAL
20 degrees celcius
60 degrees celcius
COLD
WARM
Question Hot or cold?
HEAT FLOW
COLD
HOT
Experiment DO AT HOME
The SAME WATER feels cold to one hand feels warm to the other hand. Why?
HEAT flows from object at higher temperature to object at lower temperature
37 degrees celcius
NORMAL
20 degrees celcius
60 degrees celcius
COLD
WARM
Let's revise
- Whenever the temperature of any object increases or decreases , it is due to heat transfer
- Heat always flows from high temperature (hotter things) to low temperature (cooler things)
- Hot and cold are relative terms - w hether something is hot or cold depends on what you are comparing it with
Conduction
By Arnav .
