Thermal Energy & Heat
THERMAL ENERGY & MATTER: Journal 1. In which direction does heat flow spontaneously? 2. Define TEMPERATURE 3. 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.
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
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- 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 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
Specific Heat – amount of heat needed to raise ONE gram of a material ONE degree Celsius.
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°CSpecific heat of lead = 0.46J/g°C
3 methods of heat transfer: conduction, convection, and radiation. 10 Heat Transfer: Crust forming on the surface of lava is an example of a change of state by transferring heat from the hot lava to the cooler air surrounding the lava.
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. Must be Touching!
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
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!
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?
16 Where does heat transfer on this beach? Label at least four examples of heat transfer on the picture.
Diagram Answers: 17
Methods of Heat Transfer Think-Pair- Share!! Discuss examples of each type of heat transfer with a partner for two minutes. 18
Methods of Heat Transfer Conduction: Heat transferred by touching 19 Convection: Heat transferred by the motion of a substance Radiation: Heat transferred through as waves through space