3.3 Heat Transfer

Define specific heat capacity

energy needed per unit mass (1kg) to raise temp by 1K

Specific heat capacity of water

4200J/kgC

Specific heat capacity formula

Q=mcChangeT

What is Q?

thermal energy

Heat capacity (C) formula

C=mc

What is c?

specific heat capacity

Define specific latent heat

amt of energy per kg needed to change phase of substance at const temp

Thermal energy (Q) formula (w/ latent heat)

Q=mL

What is thermal expansion?

when material is heated at const pressure

List the order of expansion of states, from least to most

solid, liquid, gas

Uses of thermal expansion
1. f__ alarms
2. large br__
3. r__ tracks
4. th__

fire, bridges, railway, thermometers

Consequences of thermal expansion
> joints in b__ can collapse
> road surfaces can have p__

bridges, potholes

Conduction occurs mainly in

solids

Convection occurs mainly in

liquids & gases

Define conduction

heat transfer thru solids

Why are metals good conductors?

dense, many free valence electrons

Define convection

heat transfer thru fluids

In convection, why do particles move places?

density changes

What happens in convection?

heated particles rise up (less dense) and go back down

Example of convection in liquid

boiling water

Example of convection in gas

sea breeze

Does radiation need a medium (vacuum, gas, liquid) to pass through?

no

Define radiation

infrared radiation transfers heat without medium

The (darker/lighter) the colour, the better the emission & absorption of IR

darker

Latent heat at m.p. (solid - liquid)

fusion

Latent heat at b.p. (liquid - gas)

vaporisation

Application for thermal expansion (long metal thing?)

bi-metallic strip