Heat energy is present in every object above absolute zero. How do we know that heat is present in every object? Temperature of the body is an indication.
(Absolute zero is the lowest temperature possible and is equal to -273oC).
Are heat and temperature one and the same?
No. They are different. Heat is a form of energy and temperature represents the degree of hotness of a body. We can say, 'Heat is the cause and temperature is the effect'.
Consider this example- A and B are two glass vessel interconnected by tube with a valve. In the first picture the vessels are filled with water to different levels. The valve is closed. In picture (2), the valve is open. We observe that water flows from vessel A (in which water level is higher) to vessel B (in which water level is lower) until the levels are equalized. Thus, water flows from higher level to a lower level until the levels are equalized.
Water flows from higher level to lower level
Similarly, if two substances at different temperatures are mixed, heat flows from hotter body to the colder one until their temperatures are equalized.
Thus, we can say that, 'temperature is that condition which decides the direction of heat flow when two bodies are mixed together'.
