Topic 6: Transferring Energy Science 7, Unit 3

Energy Source Energy Source: An object or material that can transfer energy to other objects. Example: the sun

There are three common ways energy can be transferred: Radiation Conduction Convection

Radiation Radiation is the transfer of energy where there is no movement of matter. Radiation is where energy spreads outward from a central point. Radiant energy can also be called electromagnetic radiation (EMR). EMR can travel through vacuum, air, glass and other materials.

EMR Types There are 4 forms of EMR: Radio waves Microwaves Visible light X-rays

All forms of radiant energy have the following characteristic in common: They behave like waves They can be absorbed and reflected by objects They can travel across empty space at 300 000 km/s

Activity: Comparing Surfaces

Conduction Conduction is the transfer of energy through direct collisions between particles.

Conduction The particles closest to the source of heat absorb the energy and start moving faster.

Conduction 2. The faster moving particles hit the particles closest to them. This increases their energy and accelerates their speed.

Conduction 3. Then the other particles that were hit collide with the other particles next to them and so on. Therefore the thermal energy is transferred throughout the substance.

Conductors Metals are examples of good heat conductors. Conductors: materials that transfer energy effectively

Insulators Other solids, like glass and wood, do not transfer thermal energy as well as metals with conduction. These are called heat insulators. Insulators: Materials that slow the transfer or conduction of thermal energy from one object to another; examples include fibre glass and Styrofoam cups.

Convection Convection: the process in which a hot fluid moves and transfers thermal energy. Fluid: materials that flow (ie. Air, water)

Convection 1. The particles close to the source of heat absorb the thermal energy and heat up.

Convection 2. The heated particles gain energy and become less dense. This causes them to rise.

Convection 3. This causes the colder particles to descend and replace the particles that have already been heated up.

Convection Currents A convection current is the continuous movement of a fluid (liquid or gas). The warm fluid rises and cools, and then the cooled particles descend towards the source of heat. The fluid is heated again and the cycle starts over.

Activity: Indicate if each of the following is an example of radiation, conduction or convection: The rays of the sun heat up your skin during a nice sunny day. A chef is heating up some food on the stove. An oven that uses air circulation to heat up food. A solar powered calculator. A fire that burns in a fireplace. An electric blanket that warms up your bed. A furnace that distributes heat throughout your house. Which method of heat transfer is the easiest to understand? Why? Which method of heat transfer is the hardest to understand? Why?

Energy Transfer Systems There are 5 common characteristics for all energy transfer system: 1. Source of energy The part of the system where we find a high concentration of energy Gives energy to the rest of the system The initial form can be mechanical, chemical, nuclear or electrical

Energy Transfer Systems There are 5 common characteristics for all energy transfer system: 2. Direction of energy transfer The energy is always transferred from away from the source. The transfer continues until the system reaches a uniform temperature

Energy Transfer Systems There are 5 common characteristics for all energy transfer system: 3. Transformations Energy can be transferred from one form to another

Energy Transfer Systems There are 5 common characteristics for all energy transfer system: 4. Waste heat - Energy is always lost in the form of heat

Energy Transfer Systems There are 5 common characteristics for all energy transfer system: 4. Control system - The systems include a mechanism for regulating transfers

Features of Energy Transfer Systems – cont. A. The moving fist (energy source) has a large amount of energy.

Features of Energy Transfer Systems – cont. B. Most of the energy is transferred to the entire volleyball, which moves away rapidly.

Features of Energy Transfer Systems – cont. C. Some energy is transferred to individual particles in the skin and the volleyball, which vibrate more rapidly, producing a temperature increase.

Features of Energy Transfer Systems – cont. D. Energy is transferred from the ball to the floor. Particles that make up the floor vibrate more rapidly, producing a temperature increase.

Features of Energy Transfer Systems – cont. E. Energy is transferred by conduction to nearby particles in the floor.

Features of Energy Transfer Systems – cont. F. Convection currents transfer energy through the air.

Features of Energy Transfer Systems – cont. G. Energy is also transferred to air particles by compressing them and starting a sound wave. The sound wave distributes this energy throughout.

Topic 7: Sources of Thermal Energy Science 7, Unit 3

Sources of Thermal Energy There exist several sources of thermal energy: Chemical energy Electrical energy Mechanical forces Geothermal energy Solar energy Wind energy

Chemical Energy Chemical energy is formed when we burn things such as wood and coal.

Electrical Energy There exists many ways to produce electrical energy. For example, hydroelectric dams transform the energy from moving water to electrical energy. We can also use the sun, the wind and burning fossil fuels.

Mechanical Energy Mechanical forces push or pull objects. They often release thermal energy from the friction of the different parts rubbing together.

Geothermal Energy Geothermal energy is comes from the center of the earth. Volcanos and other heat sources (eg. Banff hot springs) demonstrate that there is very hot matter under the Earth’s crust.

Geothermal Energy The hot matter can heat water, which turns to steam. This steam can be used to turn turbines and generate electricity. This form of energy is a good solution to replace the diminishing reserves of fossil fuels.

Solar Energy Solar energy comes from the sun. It is non-polluting and inexhaustible (never runs out).

Solar Energy There are 2 general ways to use solar energy to heat buildings: 1. Passive solar heating Uses materials that will absorb, store and release solar energy.

Solar Energy There are 2 general ways to use solar energy to heat buildings: 2. Active solar heating - Uses mechanical devices such as fans, for storing and distributing thermal energy.

Wind Energy Wind energy is the energy of moving air. It is a result of solar energy.

Renewable Energy Sources (5:55)

Other Forms Fossil fuels are a chemical product made from plants and other organisms that have decomposed. Fossil fuels take millions of years to form. They are the main energy source for Alberta and throughout the world.

Other Forms When fossil fuels are burned, they produce a gas, carbon dioxide, which produces harmful effects for the environment, like climate change. Examples of fossil fuels are petroleum, natural gas, and coal.

Greenhouse Gases The greenhouse effect is the increase of the average temperature of the Earth. This is caused by greenhouse gases, like carbon dioxide, that prevent heat from escaping our atmosphere.

Greenhouse Effect

Thermal Pollution Thermal pollution is when the environment heats up due to human activities. Ex: combustion of fossil fuels

Cogeneration Cogeneration is a method of energy conservation by which heat or energy released by an industry is used by another industry. This reduces the greenhouse effect.

Non-Renewable Resources Resource that takes millions of years to form and runs out after we use all of it

Renewable Resources Renewable resources Resource that can be recycled or replaced by natural processes in less than 100 years

Topic 8: Conserving Fossil Fuel Resources Science 7, Unit 3

Fossil fuels have been a big benefit for Albertans: They are a key part of Alberta’s economy They provide jobs and money Over 80% of the Alberta’s electrical energy comes from burning coal

The downside of fossil fuels include: Limited available (non-renewable resource) Pollution

Programmable thermostats, recirculating hot water systems, and other technologies have provided many ways to save energy (and money) at home.

Thermal Energy Movers: Devices that transfer thermal energy from one location to another location at a different temperature. Refrigerators and air conditioners are both thermal energy movers

Refrigerants: Liquids that evaporate easily at low temperatures. Refrigerators and air conditioners rely on the process of evaporation and condensation. They use refrigerants to remove thermal energy. Refrigerants: Liquids that evaporate easily at low temperatures.

The problems with thermal energy movers similar to fossil fuels: The amount of energy they use taxes the non-renewable energy resources. The chemicals that are used as refrigerants are harmful to the environment. solar roadways 7 min