ENERGY TRANSFER HEAT The major source of

ENERGY TRANSFER: HEAT

The major source of energy is the SUN. In photosynthesis plants convert sunlight into stored energy in the plants. Animals and humans eat the plants to get energy. The human body “burns” this stored energy in units called Calories. One Calorie is equal to 4. 18 J. The human body stores energy in Calories and will utilize “burn” this energy as needed.

What is Thermal Energy?

Particles of matter are in constant motion. This motion relates directly to the state of matter of the object (solids, liquids, or gases). Temperature affects how fast these particles move. The higher the temperature the faster the particles move. Moving particles possess kinetic energy. Temperature is defined at the average kinetic energy of the particles of an object.

Thermal Energy is the sum total of all of the energy of the particles of an object. Thermal energy and temperature are related though DIFFERENT. Temperature is the average kinetic energy of the particles of an object. Thermal energy is the total amount of energy of the particles of an object. A bathtub full of water at 100 o. F has more thermal energy than a thimble of water at 100 o. F. The temperature is the same but the total amount of energy is different. The bathtub has more energy.

What is heat? heat Heat is thermal energy that flows from something at a higher temperature to something at a lower temperature. What is specific heat? heat Specific heat is a property of matter which determines how readily a material is to absorb heat and change temperature. Specific Heat is defined as the amount of heat energy needed to raise the temperature of 1 kg of a substance by 1 o. C or 1 K.

Did you notice that water has a very high specific heat, whereas iron has a low specific heat? Water requires a lot of heat energy to raise its temperature.

Metals require little energy to raise its temperature. Thermal energy can be calculated using the following formula:

Try this one!! Answer = 376 J/kg K Did you do this problem?

Transferring Thermal Energy How is Thermal Energy Transferred? YOU MUST KNOW THIS!!!!! Conduction – direct contact Convection – through a fluid Radiation – by electromagnetic waves

What is heat transfer by conduction? conduction Heat transfers as particles of an object increase their collisions as heated. These collisions transfer the heat energy through the object by colliding with adjacent particles.

What is heat transfer by convection? convection Heat is transferred through a substance through currents. This occurs in fluids (liquids AND gases) Convection currents are caused by heating of a liquid or gas, the liquid or gas rises, then cools and falls. This occurs in the mantle of the earth And in the atmosphere. Most of our weather patterns are the result of convection currents in the atmosphere.

What is heat transfer by radiation? Radiation is heat transfer by electromagnetic waves. These wave may pass through all states of matter and also through NO matter – such as the vacuum of space. This energy is often called radiant energy. Radiant energy from the sun travels through the vacuum of until it reaches the earth.

How is heat flow controlled? Insulators – a material which does not allow heat to pass through it easily. Some animals have good insulation to survive severe winters.

Buildings and houses are insulated so that heat does not pass out of (winter time) and into (summer time).

What are some other uses of insulation?

Using heat – How do we use heat in our lives? Forced-Air Systems – a fuel is burned in a furnace and a fan circulates the heat in the house

Radiator Systems – closed metal containers that contain hot water or steam. The thermal heat is transferred to the air and circulated by convection currents. Electric radiators – heat metal coils which transfer thermal heat to the surrounding air.

Refrigerators, air conditioners, and heat pumps – how do they work? A coolant is circulated through pipes by a compressor. When the pipes get small and narrow the coolant compresses and changes to a liquid giving off heat energy. When the pipes get larger, the coolant changes from a liquid to a gas (evaporates) causing the area to absorb heat and get cooler

The human coolant - In-built cooling system The human body has a cooling system which function automatically – perspiration – sweat. Like a refrigeration system, the evaporation of the sweat from the surface of the body causes energy to be absorbed from the skin, causing the skin to feel cooler. No sweat!!!