Thermal Energy & Heat Heat and Its Uses

16.1 Thermal Energy and Matter Thermal Energy & Heat 16.1 Thermal Energy and Matter

THERMAL ENERGY & MATTER: Journal In which direction does heat flow spontaneously? Define TEMPERATURE How is THERMAL ENERGY transferred? What are the factors that determine the THERMAL ENERGY of a material? Which type of material heats more, one with a high specific heat, or one with a low specific heat? 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 & MATTER Heat 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 there are 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

16.2 Heat and Thermodynamics Thermal Energy & Heat 16.2 Heat and Thermodynamics

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? 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 & Heat 16.3 Using Heat

THERMAL ENERGY & MATTER: Journal Define Convection, Conduction and Radiation Give an example of each. Write a sentence describing how each is important to our everyday lives. How do we use heat in our everyday lives?

PART 2 - USING HEAT HEAT ENGINES The two main types of heat engines are External combustion and Internal Combustion External = power plants Internal = car engine

Water is heated by a fuel and the pressurized steam spins a turbine. PART 2 - USING HEAT External 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 HEAT HEAT ENGINES External combustion – nuclear power plants.

Internal combustion – car engines. 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.