The Nature of Energy

What is Energy The ability to do work or cause a change is called energy. When an organism does work some of its energy is transferred to that object.

Operational Definition If a system has energy it has the ability to do something or is actually doing something. A system can contain many forms of energy.

Kinetic Energy Energy of motion is kinetic energy. Two general kinds of energy – kinetic and potential.

Kinetic Energy depends on Mass and Velocity As mass increases so does the kinetic energy. As velocity increases so does kinetic energy.

Potential Energy Energy that is stored is potential energy. This type of energy has the potential to do work. Elastic Potential Energy – is associated with objects that can stretch or compress.

What is work? Work is the transfer of energy through motion. The amount of work done depends upon two things: 1. The force exerted 2. The distance over which force is applied.

Gravity? Gravitational potential energy depends on the height of the object. The more mass you have, the more potential energy you have PE = weight x height

Background info: Gravitational PE on an object is = to the work done to lift it. Work = Force x Distance Unit for work and energy is the joule which is = to 1 Newton meter.

Forms of Energy Mechanical Energy: Thermal Energy Chemical Energy Electrical Energy Electromagnetic energy Nuclear Energy Sound Light

Mechanical Energy Energy associated with the motion or position of an object. Can be Kinetic or Potential. Associated with work output. A lever makes work easier. Creates mechanical advantage. Work done by machines gives mechanical efficiency and advantage.

Thermal Energy Total energy of the particles in an object. When thermal energy increases, its particles move faster, making it feel warm to the touch.

Chemical Energy Chemical energy is potential energy stored in chemical bonds that hold the chemical compounds together.

Electrical Energy Moving electrical charges create electricity and the energy they carry is called electrical energy.

Electromagnetic Energy It is energy that travels in waves. The waves have some electrical properties and some magnetic properties. Light, infrared, microwaves.

Nuclear Energy Nuclear energy is generated from the nucleus of the atom (protons and neutrons). Energy is released from the nuclei of atoms like uranium.

Sound Energy Energy produced by vibrations causes sound. Sound energy is a form of both potential and kinetic energy.

Light Energy Light energy can cause chemical reactions to occur. It provides the energy necessary for photosynthesis in which green plants make their own food through a series of chemical reactions. It also stimulates chemical reactions in your eyes so that you can see.

Conversions A change from one form of energy into another.

Law of Conservation of Energy This law states that energy can change forms but energy cannot be created or destroyed under ordinary conditions.

A system contains Input – the things that go into a system to make it work. Output – the things coming out of a system. A system must contain input and output.

Balanced Systems Many systems require that the input and output of the system are balanced which is not always easy. Consider your own body, what will happen if the input of energy is greater than the output of energy?

Electric Power Power is the rate at which work is done in a unit of time. Power = work/time Measured in watts

Energy Sources Discuss cost and benefits of each.

Fossil Fuels When plants and animals die, they are covered with layers of sand, mud, ash, and other matter. Great pressure, heat, and bacterial action acts on these buried organisms forming fossil fuels. Fossil fuels are commonly called crude oil. There are several kinds of crude oil. Some of the best comes from Alaska.

Fossil Fuels Fuels store energy in the form of Chemical Potential Energy. Fossil fuels include: coal, petroleum, gas. The energy fossil fuels store came from the sun. Fossil fuels can be burned to release the Potential chemical energy this process is called combustion. PE to thermal Energy.

Examples of Fossil Fuels Coal: three types. Petroleum Natural gas

Non-renewable resources All fossil fuels are non-renewable resources – they cannot be replaced after they are used. This is why conservation is so important.

Alternative Energy Sources The need for alternatives

Solar Energy The sun is the Earth’s only source of new energy.

Hydroelectricity Hydroelectricity is the electricity produced by the energy of moving water. Dams are built to store water. When the water is allowed to rush out through the tunnels it spins a turbine, rotating the shaft of an electric generator to produce electricity.

Tidal Energy The flowing water at low tied spins a turbine, which operates an electric generator.

Wind Energy A windmill is a turbine that is turned by wind as it spins it rotates an electric generator A cost of wind energy is that it looks ugly…

Geothermal Energy The inner parts of the Earth contain thermal energy. Wells can be drilled and the steam from within the Earth can be used to rotate turbines.

Solar energy drives the water Cycle. The process below explains.