Physics Yr 9 exam - thermal energy and energy transfers.

Thermal energy

The total kinetic energy of the particles in a substance due to their motion.

Heat transfer

The process by which thermal energy is transferred from one object to another, occurring through conduction, convection, and radiation.

Conduction

The process of heat transfer through direct contact between materials, most effective in solids due to closely packed particles.

Convection

The flow of heat energy by the movement of a fluid from a high temperature region to a low temperature region.

Radiation

The transfer of heat energy through infrared radiation without the need for particles.

Insulation

Materials like foam or wool that reduce thermal transfer by conduction.

Double glazing

A method of trapping air between layers of glass to reduce conduction and convection.

Efficiency formula

Efficiency = (useful energy output / total energy input) x 100.

Principle of conservation of energy

Energy cannot be created or destroyed; it can only be transferred from one type to another.

Sankey diagram

A diagram that shows how energy is transferred in a system, with thicker arrows representing more energy.

what are the eight energy stores? 

chemical, kinetic, gravitational, elastic, thermal, magnetic, electrostatic, nuclear

what are the 4 energy transfers?

mechanically, electrically, by heating, by radiation (light and sound)

How are emission and absorption of radiation related to surface and temperature?

Objects give out and take in heat by radiation. Hotter objects emit more radiation. Dull, black surfaces are good at both absorbing and emitting radiation, while shiny, light surfaces absorb and emit very little. So good absorbers are also good emitters, and poor absorbers are poor emitters.

What is the role of convection in everyday phenomina

Cooking - ensures an evenly cooked meal. Heating a room - Convection allows the warm air to circulate and warm all of the room