6.1: Energy

6.1: EnergyEnergy: Energy is the capacity to do work.2. Energy is the limit of an object to perform work S.I Unit:Joule (J) Work means when a body moves to achieve a purpose In order to work energy is either transferred or converted.

Different Forms of Energy:Kinetic Can be used to do work . Potential: Chemical Gravitational Potential Elastic.

There are 2 types of energyKinetic energy: Due to motionPotential Energy: Energy due to positionEnergy is a scalar quantityEnergy/Work=F*dEnergy remains conserved it is not wasted.Chemical potential energy: Energy stored in an object due to the arrangement of it's electron.BatteriesFoodFossil fuelGravitational potential energy:Energy stored in it's body due to it's height from the ground.Elastic potential energy:Energy in an object due to it's elastic deformationFor e.g: a rubberband

Other forms of energy:1. Electrical energyEnergy of an electric charge due to it's motion or position.2.Light energylight is an electro -magnetic wave that is visible to the naked eye. Made up of electric and magnetic fields oscillating at a frequency.3. Thermal energy:heat energy4. Nuclear energy:

PRINCIPLE OF CONSERVATION OF ENERGY:The principle of conservation of energy states that energy cannot be created or destroyed but can be conserved and transferred.The diagram below show the energy transfer of a Mobile phone.

Efficiency:Total energy output=Total energy inputEfficiency= Output x 100 InputSummary of all the work:Energy is the capacity to do workCannot be created or destroyedEfficiency= Output x 100 Input

6.2: WORK

Work done only is when an object happens to move under the influence of a force applied.W=FxdS.I.Unit=Joule(J)WORK DONE=ENERGY TRANSFERREDWORK AND IT'S RELATION WITH KINETIC ENERGY:kinetic energy= 1 x Mv•2 2Potential energy= Pe=mgTotal energy= gravitational energy+kinetic energy =mgh+1/2mv2

Power:Rate of work done.Power = work done Time takenProblem time:A bulb rated 60 W coverts 20% energy to supply light energyCalculate the quantity of light energy emmited in 3 minutes.P= work done/time taken40=w/1807200(j) 20 x7200100=14400KJ

By the Principle of Conservation of Energy,totalenergy of ==gravitationalpotentialenergy atpoint Q+kineticenergy atpoint Q+dissipatedenergysystem