Thermal Energy & Thermal Energy & HeatHeat

Heat and Its UsesHeat and Its Uses

Thermal Energy & Thermal Energy & HeatHeat

16.1 Thermal Energy and 16.1 Thermal Energy and MatterMatter

THERMAL ENERGY & MATTER: Journal

1. In which direction does heat flow spontaneously?2. Define TEMPERATURE3. How is THERMAL ENERGY transferred?4. What are the factors that determine the THERMAL

ENERGY of a material?5. Which type of material heats more, one with a

high specific heat, or one with a low specific heat?6. Is WORK 100% efficient? How do you know?

THERMAL ENERGY & MATTER

Work and Heat- work is never 100% efficient. Some is always lost to heat.

THERMAL ENERGY & MATTER

Heat- the transfer of thermal energy from one object to another because of a temperature difference.

In what direction does heat flow spontaneously?

FROM HOT to COLD

THERMAL ENERGY & MATTER

Temperature = measure of how hot or cold something is compared to a reference point.

Temperature is the average kinetic energy of the particles in an object.

In the image below, where is average kinetic energy greater?

Higher temperature

THERMAL ENERGY & MATTERHeat flows DOWN the bar through

COLLISIONS.Collisions transfer thermal energy from

hot to cold.

THERMAL ENERGY & MATTER

Thermal energy- total potential and kinetic energy in an object. It depends on mass, temperature, and phase of an object.If both objects are in the same phase & at the same temperature, which one has MORE thermal energy?

Because thereare MORE

particles moving around.

THERMAL ENERGY & MATTER

Thermal expansion/contraction - change in volume of a material due to temperature change.

Occurs because particles of matter collide more or less as temperature changes.

Thermal expansion Also, wrap on beaker and lava lamp

THERMAL ENERGY & MATTER

Specific Heat – amount of heat needed to raise ONE gram of a material ONE degree Celsius.

THERMAL ENERGY & MATTER

The LOWER a material’s specific heat the MORE its temperature rises when energy is added.Which will heat faster (has the lower specific

heat)?Water? Or Lead?

YES!

Specific heat of water = 4.18 J/g°C Specific heat of lead = 0.46J/g°C

Thermal Energy & Thermal Energy & HeatHeat

16.2 Heat and Thermodynamics16.2 Heat and Thermodynamics

HEAT TRANSFER

What type of HEAT TRANSFER is occurring in the pictures? Conduction, convection or radiation?

CONDUCTION – The transfer of thermal energy with no

transfer of matter.

HEAT TRANSFER

What type of HEAT TRANSFER is occurring in the pictures? Conduction, convection or radiation?

CONVECTION – The transfer of thermal energy when particles

of a liquid or gas move from one place to another

HEAT TRANSFER

CONVECTION – in the earth and sun

HEAT TRANSFER

What type of HEAT TRANSFER is occurring in the pictures? Conduction, convection or radiation?

RADIATION – The transfer of thermal energy by waves

moving through space. ALL OBJECTS radiate energy!

THERMODYNAMICS

The study of conversions between thermal energy and other forms of energy.

THERMODYNAMICS

First Law: Energy is Conserved

Thermal Energy & Thermal Energy & HeatHeat

16.3 Using Heat16.3 Using Heat

THERMAL ENERGY & MATTER: Journal

1. Define Convection, Conduction and Radiation

2. Give an example of each.3. Write a sentence describing how each

is important to our everyday lives.4. How do we use heat in our everyday

lives?

PART 2 - USING HEATHEAT ENGINES

The two main types of heat engines are External combustion and Internal Combustion

External = power plants

Internal = car engine

PART 2 - USING HEATExternal combustion – produces

electricity at power plants.Water is heated by a fuel and the pressurized

steam spins a turbine.http://www.eas.asu.edu/~holbert/eee463/coal.html

PART 2 - USING HEATHEAT ENGINES

External combustion – nuclear power plants.

USING HEAT

Internal combustion – car engines.

The fuel (gas) is compressed and ignited (lit) to drive a piston.

USING HEAT

Internal combustion – car engines.

Four-stroke engine.