States and properties of matter, kinetic theory

Phase Change

Density

Pressure

Thermal physics

Heat transfer

MYP Physics Heat Transfer Notes

How does heat move from one place to another?

Definition

Heat transfer

The movement of thermal energy from one object or region to another due to a temperature difference.

Heat transfer is the movement of thermal energy from a region of higher temperature to a region of lower temperature.

This direction is not a choice, it is a consequence of particles in the hotter region having, on average, more kinetic energy.

When energy spreads out, temperatures tend to equalize.

There are three main mechanisms of heat transfer:

Conduction (direct contact)
Convection (bulk movement of fluids)
Radiation (electromagnetic waves).

Example

If you place one hand in cold water and the other in hot water for a minute, then put both into warm water, the "cold" hand feels warm and the "hot" hand feels cool.
The warm bowl has one temperature, but each hand experiences a different direction and rate of heat transfer.

1. Conduction Transfers Energy Through Collisions In Contact

Definition

Conduction

Conduction is the transfer of heat through particle collisions.

Conduction is heat transfer through direct contact.

Energy is transferred by collisions between particles.

It occurs mainly in solids.

When two objects touch, particles in the hotter object have higher average kinetic energy.
Collisions at the boundary transfer energy to particles in the cooler object.
Conduction also moves energy through an object (for example, along a metal rod).

Tip

To reduce heat loss by conduction (for example in buildings or clothing), use materials with low thermal conductivity (insulators), increase thickness, and reduce exposed surface area.

Why Metals Conduct Heat Well

Different materials conduct heat at different rates.

Good thermal conductors transfer heat quickly (many metals).
Insulators transfer heat slowly (for example wood, plastic, and trapped air).

In metals, mobile electrons can move through the material and carry energy efficiently.

This is why strong electrical conductors like silver, copper, and gold also tend to be strong thermal conductors.

Note

The link between electrical and thermal conductivity is strong for metals because of free electrons, but it does not reliably apply to non-metals.
For example, diamond is an excellent thermal conductor but a poor electrical conductor.

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Note

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Tip

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MYP Physics Heat Transfer Notes

How does heat move from one place to another?

1. Conduction Transfers Energy Through Collisions In Contact

Why Metals Conduct Heat Well

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

How does heat move from one place to another?

1. Conduction Transfers Energy Through Collisions In Contact

Why Metals Conduct Heat Well

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

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Forces and energy8 subtopics

Heat, light and sound6 subtopics

Electromagnetism9 subtopics

Waves5 subtopics

Astrophysics3 subtopics

Atomic physics2 subtopics

MYP Physics Heat Transfer Notes

Forces and energy8 subtopics

Heat, light and sound6 subtopics

Electromagnetism9 subtopics

Waves5 subtopics

Astrophysics3 subtopics

Atomic physics2 subtopics

How does heat move from one place to another?

1. Conduction Transfers Energy Through Collisions In Contact

Why Metals Conduct Heat Well

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

How does heat move from one place to another?

1. Conduction Transfers Energy Through Collisions In Contact

Why Metals Conduct Heat Well

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account