Chapter 6 Thermal Energy Section 1 Temperature and Heat

Are Temperature and heat The same thing?? NO!!!

ARE TEMPERATURE AND HEAT RELATED?? YES THEY ARE!!

Get This! The matter around you is made up of tiny particles called what? These particles are constantly in random motion; they are always moving! Therefore they have kinetic energy

The faster something moves the more kinetic energy it has

They move faster Do particles in hot objects move slower or faster than the particles in cold objects? They move faster

What is Temperature? The measure of the average kinetic energy of the particles in the object As temp. the speed of the particles

What is the SI unit of temperature? Kelvins which is represented by a K

Why does cold butter become softer when it is left sitting out at room temperature? Because the particles in the air have more kinetic energy and collide with the slow moving particles in the cold butter

The particles in the butter also have potential energy. Here’s why… The particles in butter are attracted to each other When they are separated, they have potential energy

Thermal Energy This is the sum of the kinetic and potential energy of all the particles in an object

Fun Fact How does your body maintain its internal temperature?? By shivering!

Thermal Energy and Temperature THEY ARE RELATED When the temperature increases, the kinetic energy of the particles increases Thermal energy is the SUM of kinetic energy and potential energy and therefore it will increase when temperature increases

Thermal Energy and Mass Does the size of an object affect the thermal energy of the object? Why yes it does!

Heat The thermal energy that flows from something at a higher temperature to something at a lower temperature. It is a form of energy and what is energy measured in??

Example Making ice cream… Yum Heat flows from the warmer ice cream Ingredients to the colder salt and ice mixture. The liquid ingredients get cold enough to form solid ice cream while the ice becomes warm and melts.

Specific Heat The amount of heat that is needed to raise the temperature of 1 kg of some material by 1°C This is measured in J/(kg °C) Table 1 p. 161 lists the specific heat of certain materials

Why is water used as a coolant? It has a high specific heat and therefore can absorb heat without a large change in temperature.

Changes in Thermal Energy Equation: Q = m(Tf – Ti)C

Example Find the change in thermal energy of a 20 kg wooden chair that warms from 15°C to 25°C if the specific heat of wood is 700 J/(kg°C).

Chapter 6 Thermal Energy Section 2 Transferring Thermal Energy

Thermal Energy is transferred in 3 ways: Conduction Convection Radiation

The transfer of thermal What is conduction?? The transfer of thermal Energy by collisions Between the particles In matter

So… Thermal Energy is transferred by fast moving particles colliding with slower moving particles. When thermal energy is transferred by conduction NO matter is moved.

What do these things have What are some good Conductors?? What do these things have In common??

Convection The transfer of thermal energy in a fluid by the movement of warmer and cooler fluid from place to place

Convection Warmer fluid is less dense than cooler fluid So, think of a lava lamp What happens?

Convection The warmer fluid rises to the top until it cools and then it will sink back down to the bottom

Earth if there is no matter In space for it to travel How does the heat From the sun reach Earth if there is no matter In space for it to travel Through??

Through Radiation! The transfer of energy by electromagnetic waves No matter is needed Called radiant energy

What are some ways heat flow can be controlled?

Insulators Material in which heat flows slowly Examples: Wood Plastic Fiberglass (think of the pink insulation in your house) Air

Draw, Label, and Color! p. 170 Figure 12 Draw, label, and color the thermos

Chapter 6 Thermal Energy Section 3 Using Heat

Types of Heating Systems Forced-Air System *Most commonly used system today p. 172 Fig. 13

Types of Heating Systems 2. Radiator Systems Fuel is burned in a central furnace and heats a tank of water. Pipes carry the hot water to radiators in a building. The thermal energy from the water is transferred to the air by conduction and spreads through the room by convection. Then the cooled water flows back down the pipes and back into the water tank.

Types of Heating Systems 3. Electric Heating Systems In this system electrically heated coils are placed in floors and in walls. They heat the surrounding air by conduction. Heat is distributed throughout the room by convection.

Solar Heating *There are two types of solar heating systems Passive solar heating systems Active solar heating systems

Passive Solar Heating Materials absorb radiant energy (heat) from the Sun during the day. At night the building cools The thermal energy absorbed by the materials is released and helps keep the room warm.

Active Solar Heating These use solar collectors that absorb radiant energy from the Sun. *The solar collectors are the GIANT black panels you sometimes see on roofs. The black panels heat water in pipes and this heated water is transferred to radiators throughout the house. The cool water then returns to the solar panel.

Thermodynamics The study of the relationship between thermal energy, heat, and work There are two laws of thermodynamics: 1. First Law of Thermodynamics 2. Second Law of Thermodynamics

First Law of Thermodynamics The increase in thermal energy of a system = the work done on the system + the heat transferred to the system Basically: To temperature add heat, do work on the system, or both

Second Law of Thermodynamics Heat will not flow from a cool object to a warmer object unless work is done Heat

FYI Heat Engine Device that converts heat into work Example: Car engine *Only about 25% of heat released by gasoline is converted to work FYI

What type of combustion engine is in a car?

What type of combustion engine is in a car? An Internal Combustion Engine

What is the human coolant? SWEAT!

Explain how either a Refrigerator or air Conditioner works.