16.1 What is Energy?Energy is the ability to do work .We use energy to live and function .Without energy, living systems will dieand non-living systems will not function .The SI unit for energy is Joules ( J ).
16.2 Forms of EnergyEnergy exists in many forms. Energy in Action Stored EnergyKinetic Energy Potential EnergyHeat Energy Gravitational Potential EnergyLight Energy Elastic Potential EnergySound Energy Chemical EnergyElectrical Energy Nuclear Energy
Kinetic Energy Kinetic energy is the energy that a body has due to its motion. Any object that moves has kinetic energy. Eg. A moving car has kinetic energy
Heat Energy Heat energy is the energy that flows from a region of higher temperature to a region of lower temperature. Eg. A hot cup of tea contains heat energy.
Light Energy Light is the energy that enables us to SEE. Eg. Light energy is given out by a fire.
Electrical Energy Electrical energy is a form of energy that involves the flow of electric charges.
Gravitational PotentialEnergy Gravitational Potential Energy is the energy an object has because of its position or location. Any object that is raised from a lower position to higher position gains gravitational potential energy.
Elastic Potential Energy Elastic Potential Energy is the energy an object has when it is stretched or compressed. Eg. A stretched rubber band or a compressed spring has elastic potential energy.
Chemical Energy Chemical energy is the energy stored in fuel (eg. Petrol, Batteries, Food) that can be released through chemical reaction.
Nuclear Energy Nuclear energy is a form of energy stored in the nuclei of atoms. Eg. Atomic bombs, nuclear reactor in a nuclear power plant
16.3 Conversion of Energy Energy can be converted from one form to another.
Examples of Conversionof Energy Oven Toaster Electrical Energy Heat Energy
Examples of Conversionof Energy Television Electrical Energy Light Energy and Sound Energy
Examples of Conversionof Energy Burning Matchstick Chemical Energy Heat Energy and Light Energy
Examples of Conversionof Energy Falling Apple Gravitational Kinetic Potential Energy Energy
Examples of Conversionof Energy Atomic Bomb Nuclear Energy Heat Energy, Light Energy and Sound Energy
Examples of Conversionof Energy A person shooting a rubber band Elastic Potential Kinetic Energy Energy
16.4 Principle ofConservation of Energy Principle of Conservation of energy states that:Energy cannot be created or destroyed.It is transferred from one body to anotheror transformed from one form to another.Total energy remains constant.
Example: Piling 1. The pile hammer is raised to a height. It gains gravitational potential energy. 2. During the fall, the gravitational potential energy energy is changed to kinetic energy. 3. As the hammer hits the pile, majority of the kinetic energy is transferred to the pile driving the pile into the ground. While some is converted to sound & heat energy.
Example: Swinging of Pendulum Pendulum bob loses all its kinetic energyPendulum bob has its and gain maximummaximum gravitational gravitational potentialpotential energy and energy as it comes tozero kinetic energy at rest at its maximumPendulum bob losesthe starting position height.gravitational potential Pendulum bob starts toenergy and bob loses all its Pendulum gains lose its kinetic energykinetic energypotential energy gravitational as it and gain gravitationalswings down maximum and gain its potential energy as itkinetic energy at the lowest position swings up
Power StationA power station uses fossil fuelssuch as coal, natural gas and oil.When these fossil fuels areburnt, the chemical energystored in these fuels is releasedto boil water to form steam.The moving steam turns thegenerator.When the generator turns,electrical energy is produced.
Power StationA power station uses fossil fuelssuch as coal, natural gas and oil.When these fossil fuels areburnt, the chemical energystored in these fuels is released Energy Conversionto boil water to form steam. in Power plantThe moving steam turns the Chemical Energygenerator. Heat EnergyWhen the generator turns,electrical energy is produced. Kinetic Energy Eletrical Energy
Different types of Power Station A geothermal power plant uses heat from the earth. A hydroelectric power station uses energy from falling water. A wind turbine uses energy from wind to turn the turbines.
Conserving Energy With rapid growth in populations, urbanisation, industrialisation and globalisation, the world is consuming more energy. There is a need to conserve energy and use it wisely.
Free but expensivesources of energyEnergy from the Sun, wind, rain, tides, nuclearfuels and heat from inside the Earth can beharnessed to do work and improve our qualityof life.These alternative sources of energy are cleanand do not run out.However, they are expensive or unsuitable toharness in some places.
Plants and waste fromanimals Fuels such as biogas and alcohol are derived from biomass (plant materials or wastes from living things)
Risky Sources The production of electrical energy using nuclear fuels is cleaner than that using coal or oil. However, there is a fear of exposure to harmful radiation should an accident happen in a nuclear power plant.
In Singapore…. Singapore is a small country without natural resources. Although it is one of the major oil refinery centres of the world, it has to import oil and gas from other countries for production of electrical energy. There is a need to conserve energy, especially for Singapore.
Caring for Mother Nature Humans’ need for more and more energy has sparked the global concern that non- renewable energy sources such as fossil fuels will run out one day. The use of such fuels has heightened environmental concerns regarding air and water pollution as well as global warming.