1. Why Heat and Temperature Are Not the Same
The words heat and temperature are often used as if they mean the same thing, but they describe two very different ideas. Temperature tells how hot or cold something is, while heat refers to the energy that moves between objects because of this temperature difference. Understanding this difference clears up many confusions in thermal physics.
2. What Is Temperature?
Temperature is a measure of the average kinetic energy of the particles in a substance. It tells us the degree of hotness or coldness. Two objects can have the same temperature even if one contains much more energy than the other.
2.1. Temperature Does Not Depend on Size
Temperature is independent of the amount of matter. A cup of warm water and a bucket of warm water can both be at 40°C, even though the bucket contains far more energy.
3. What Is Heat?
Heat is the energy that flows between two bodies because of a temperature difference. Heat always moves from higher temperature to lower temperature until both reach thermal equilibrium. Heat is measured in joules, not in degrees.
3.1. Heat Depends on Mass and Temperature Change
The amount of heat absorbed or released by a substance depends on how much of it is present and how much its temperature changes. The relation is:
\( Q = mc\Delta T \)
This is why a bucket of water needs more heat than a cup to reach the same rise in temperature.
4. Key Differences Between Heat and Temperature
The two ideas differ in meaning, nature, units, and behaviour. These differences can be understood clearly by comparing them side by side.
4.1. Conceptual Differences
- Temperature tells how hot or cold an object is.
- Heat is the energy transferred from one object to another due to temperature difference.
- Temperature is a property of a body; heat is not stored—it is transferred.
- Heat flow stops when temperatures equalize.
4.2. Physical Nature
- Temperature relates to average kinetic energy of particles.
- Heat relates to total energy transferred due to this difference.
4.3. Units Used
- Temperature: measured in °C, °F, or K.
- Heat: measured in joules (J) or calories (cal).
4.4. Mass Dependence
- Temperature does not depend on the amount of substance.
- Heat depends strongly on mass and specific heat.
5. Real-Life Examples
- A bathtub of warm water may be at the same temperature as a cup of warm tea, but the bathtub contains much more heat because it holds more water.
- Touching a metal object feels colder than touching wood at the same temperature because metal conducts heat away from the hand faster.
- Food cools down as it loses heat to the surrounding air until both reach the same temperature.
6. Summary Table: Heat vs Temperature
| Heat | Temperature |
|---|---|
| Energy in transit due to temperature difference. | Measure of the degree of hotness or coldness. |
| Depends on mass, specific heat, and temperature change. | Independent of mass. |
| Measured in joules (J). | Measured in °C, °F, or K. |
| Flows from higher to lower temperature. | Does not flow; it is a property. |
| Stops flowing at thermal equilibrium. | Equal in both objects at equilibrium. |