# Confusing heat transfer

• jangheej
In summary, the conversation discusses the confusion surrounding heat transfer in the context of immersing a red hot wire into water with small particles floating on the surface. The kinetic theory of matter is initially proposed as an explanation, but the exact mechanism of heat transfer is questioned. The possibility of convection is raised, and the energy increase of water molecules upon hitting the wire is also considered. The use of glitter as the particles in the experiment and their relation to thermal equilibrium with water molecules is also discussed. It is mentioned that conduction applies to all phases of matter and can occur in both stationary and moving substances.

#### jangheej

confusing heat transfer...

hi
im really confused about the exact heat transfer mechanism of the phenomenon i observed
the situations simple: if you immerse a red hot wire into water with small particles floating on the surface, the particles move really fast.

at first, i thought it could be explained simply by the kinetic theory of matter.
the kinetic energy of particles increase and they move fast.

1. but, after thinking more deeply about I am not so sure how exactly the heat is transferred.
conduction doesn't seem like it since conduction applies to "solids" or "stationary liquid".
but in this case, the water molecules move very fast as well.
so, if that's the case, it seems like a "bulk motion", so does that mean this is a case of convection?

2. also, thinking about the very moment that the water molecule hits the wire and bounces off... by how much does the kinetic energy of the water molecule increase? is it possible to calculate?

3. i used the glitter as the particles in my experiment, which is relatively large.
so, can i still think of it as brownian motion? can i think of the particles suspended in the liquid and therefore in thermal equilibrium with the water molecules??

help me please! :0

Where did you get the idea that conduction only applies to solids and stationary liquids? Put any two masses into physical contact. If the two masses have different temperatures, then conduction will occur. The net heat transfer will be from the hotter to the cooler. This applies to all phases of matter: solids, liquids, gases, and plasmas. It occurs if the matter is stationary or if it is in motion.

As a practical consequence of this principle, most of the heat conducted from the Earth to its atmosphere is from a moving liquid (the world ocean) to the moving air immediately above it.

## 1. What is heat transfer?

Heat transfer is the movement of thermal energy from one object to another due to a difference in temperature. This can occur through three main mechanisms: conduction, convection, and radiation.

## 2. How is heat transferred?

Heat can be transferred through conduction, which is the transfer of heat through direct contact between two objects; convection, which is the transfer of heat through the movement of fluids; and radiation, which is the transfer of heat through electromagnetic waves.

## 3. What is the difference between thermal conductivity and specific heat?

Thermal conductivity is a measure of how well a material can conduct heat, while specific heat is a measure of how much heat energy is required to raise the temperature of a material by a certain amount. In other words, thermal conductivity relates to the rate of heat transfer, while specific heat relates to the amount of heat needed for a temperature change.

## 4. How does heat transfer affect everyday life?

Heat transfer is important in many everyday activities, such as cooking, heating and cooling buildings, and even our own bodies regulating temperature. Understanding heat transfer can also help in designing more efficient technologies and processes.

## 5. How can heat transfer be controlled or manipulated?

Heat transfer can be controlled or manipulated through various methods, such as using insulation to reduce conduction and convection, using reflectors to reduce radiation, or using heat exchangers to transfer heat between fluids. The choice of method depends on the specific situation and desired outcome.