MYP Physics Heat Transfer Notes

How does heat move from one place to another?

1. Heat transfer is the movement of thermal energy from a region of higher temperature to a region of lower temperature.
2. This direction is not a choice, it is a consequence of particles in the hotter region having, on average, more kinetic energy.
3. When energy spreads out, temperatures tend to equalize.
4. There are three main mechanisms of heat transfer:
   1. Conduction (direct contact)
   2. Convection (bulk movement of fluids)
   3. Radiation (electromagnetic waves).

1. Conduction Transfers Energy Through Collisions In Contact

1. Conduction is heat transfer through direct contact.
2. Energy is transferred by collisions between particles.
3. It occurs mainly in solids.
   1. When two objects touch, particles in the hotter object have higher average kinetic energy.
   2. Collisions at the boundary transfer energy to particles in the cooler object.
   3. Conduction also moves energy through an object (for example, along a metal rod).

Why Metals Conduct Heat Well

1. Different materials conduct heat at different rates.
   1. Good thermal conductors transfer heat quickly (many metals).
   2. Insulators transfer heat slowly (for example wood, plastic, and trapped air).
2. In metals, mobile electrons can move through the material and carry energy efficiently.
3. This is why strong electrical conductors like silver, copper, and gold also tend to be strong thermal conductors.