Complete CRCT Warm-up for Thursday, Jan. 27

Please get your notes out.

REMINDER--- due tomorrow!

1) Practice Sheet #19

2) Machine Design Project

THURSDAY, JANUARY 27, 2011

1. One property that all particles of matter have is they move constantly.

TRUE

2.Name the state of matter in whicha.Particles are the closest

together

b.Moving the fastest

c.Have a constant volume but not a constant shape 

-- SOLID

-- GAS

-- LIQUID

2.Name the state of matter in which

d. Electrons have separated from the nucleus

e.No definite shape or volume

f. Particles are close together but are moving past each other  

--PLASMA

-- GAS

-- LIQUID

Recall: Thermal energy travels as heat from a material of higher temperature to a material of lower temperature. Thermal energy will flow from warmer objects to cooler ones until the temperature equalizes.

Method #1 Conduction – transfer of thermal energy through matter by direct contact of particles

Transfer by Collisions

Conduction can take place in solids, liquids and gases.

Matter must be present for conduction to take place!

Examples:

Heating a pan on a stove (pan heats up by conduction) or place a spoon in a bowl of soup (spoon heats up by conduction)

Method #2 Convection – transfer of thermal energy by bulk movement of matter

Method #2 Transfer by currents

Convection can take place in fluids (materials that flow). Liquids and gases are fluids. Currents carry less dense, warmer material up while cooler, denser material sinks.

Matter must be present for convection to take place!

Examples:

Ocean currents, wind, boiling water

Method #3Radiation – transfer of thermal energy in the form of waves.

Transfer by WAves

Energy that travels by radiation is often called radiant energy. Only radiant energy that is absorbed changes into thermal energy.

Examples: Microwave heating food, sun’s energy heating a sidewalk

Different materials absorb radiant energy differently.Material EffectShiny ________________Dull ________________Dark colors ________________Light colors ________________

Different materials absorb radiant energy differently.Material EffectShiny Reflects radiant energyDull Absorbs radiant energyDark colors Absorbs radiant energyLight colors Reflects radiant energy

Most matter is divided into two groups – matter that easily allows heat to flow through it or matter that does not allow heat to travel easily through it.

Good thermal conductor – materials with many free electrons that can easily transport (atomic) kinetic energy

Examples: iron, aluminum, silver copper

Insulators – materials that do not allow thermal energy (heat) to move easily through them

Examples: wood, plastic, (trapped) air, plastic foam