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### College Physics (Urone)

Book edition 1st Edition
Author(s) Paul Peter Urone
Pages 1272 pages
ISBN 9781938168000

# What are the main methods of heat transfer from the hot core of Earth to its surface? From Earth’s surface to outer space? When our bodies get too warm, they respond by sweating and increasing blood circulation to the surface to transfer thermal energy away from the core. What effect will this have on a person in a $${\rm{40}}{\rm{.}}{{\rm{0}}^{\rm{o}}}{\rm{C}}$$ hot tub? Figure shows a cut-away drawing of a thermos bottle (also known as a Dewar flask), which is a device designed specifically to slow down all forms of heat transfer. Explain the functions of the various parts, such as the vacuum, the silvering of the walls, the thin-walled long glass neck, the rubber support, the air layer, and the stopper.

Heat transfer from the core of the Earth to its surface takes place through conduction and convection. Heat transfer from the earth’s surface to outer space takes place through radiation and convection.

A person in a $${\rm{40}}{\rm{.}}{{\rm{0}}^{\rm{o}}}{\rm{C}}$$ tub emits heat energy to maintain normal body temperature.

Different parts of the thermos bottle help to prevent heat transfer through conduction, convection, and radiation.

See the step by step solution

## Step 1: Explain the methods of heat transfer between the earth’s surface and its core

The core of the earth has a higher temperature than the earth’s surface. The heat from the core is transferred to the surface through conduction and convection. Conduction is the process in which thermal energy is transferred from a high-temperature region to a lower-temperature region. In convection, the heat energy is transferred through the movement of particles. When the fluid in the earth's core is heated, the molecules in the core will move towards the cooler area and heat that area. Ultimately, it will heat the surface.

Through radiation and convection, heat transfer from the earth’s surface to outer space is taking place. Radiation is the transmission of energy in the form of waves through space. As a result, particles from the earth's surface heat up outer space via convection and radiation.

## Step 2: Explain how body maintains temperature when placed in a $${\rm{4}}{{\rm{0}}^{\rm{o}}}{\rm{C}}$$

Heat travels from a higher temperature to a lower temperature area. That is why our bodies emit heat in the form of sweat. When a person is in a $${\rm{40}}{\rm{.}}{{\rm{0}}^{\rm{o}}}{\rm{C}}$$bath tub, heat will flow from the tub to the body because the body temperature is $${\rm{37}}{\rm{.}}{{\rm{0}}^{\rm{o}}}{\rm{C}}$$, which is lower than the temperature in the bathtub. In order to maintain this body temperature, the body emits heat into the atmosphere by increasing the rate of blood flow. Thus, the body temperature is maintained.

## Step 3: Explain the functioning of different parts of a thermos bottle.

The main purpose of a thermos bottle is to prevent heat transfer across the bottle. The various parts of the bottle are vacuum, silver walled layer, thin-walled neck, rubber support, air layer, and stopper. They all have their own functions, as follows:

• Vacuum: prevents heat transfer between the outside environment and the internal region of the bottle. It prevents conduction and convection.
• Silver wall: reflects the radiated heat from the water inside the bottle. Thus, it prevents heat transfer through radiation.
• Thin-walled long glass neck prevents heat transfer through convection by obstructing fluid flow.
• Rubber Support: It prevents conduction because it is an insulator. So, the heat won’t get lost through conduction.
• Air layer: reduces conduction because it acts as a poor conductor.
• Stopper: prevents heat transfer through convection by stopping the air from inside and outside of the bottle.

So, the different parts of the thermos bottle prevent heat transfer by preventing conduction, convection, and radiation.

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