A girl pours hot water into a bottle and a Thermos flask. She notices that the bottle gets hotter than the Thermos flask. (a) By what process does heat from the water in the bottle reach her hand?
Answer (1)
In this scenario, the process through which heat from the water in the bottle reaches the girl's hand is called conduction .
Conduction is a mode of heat transfer that occurs through direct contact. This process happens when heat travels from one particle to another within a material, or between materials that are directly in contact. In the case of the bottle:
Direct Contact: When the girl pours hot water into the bottle, the inner surface of the bottle comes in direct contact with the water, which is at a higher temperature.
Heat Transfer: The heat from the hot water is transferred to the material of the bottle. The molecules within the bottle material begin to vibrate more rapidly as they absorb energy (heat).
Conduction to Hand: The outside surface of the bottle gets heated up because of these vibrations, and when the girl's hand touches it, the heat is conducted from the bottle to her hand.
The Thermos flask, on the other hand, is designed to prevent heat transfer. It typically has a vacuum layer, which reduces heat loss through conduction, convection, and radiation. That's why the Thermos flask remains relatively cooler externally than the regular bottle when filled with hot water.
