Energy and Efficiency

• electric fire = electric energy to heat energy
• falling object = gravitational potential energy to kinetic energy
• battery = chemical energy to electric energy
• dynamo = kinetic energy to electric energy
• tree = light energy to chemical energy
• hitting drum = kinetic energy to sound energy
• hot object = heat energy to light energy
• light bulb = electric energy to light energy
• electric motor = electric energy to kinetic energy
• leg muscles = chemical energy to kinetic energy
• catapult = strain energy to kinetic energy
• glow worm = chemical energy to light energy
• loudspeaker = electric energy to sound energy
• sound absorbing cloth = sound energy to heat energy
• atom bomb = nuclear energy to kinetic/light/heat/sound energy
• gas fire = chemical energy to heat energy
• steam engine = heat energy to kinetic energy
• friction = kinetic energy to heat energy
• microphone = sound energy to electric energy

Energy cannot be created or destroyed, only transfered between different forms. energy tends to dissapate (spread) as less useful forms i.e. heat.

forms of energy

CAMELS GUTS

chemical, atomic/nuclear, movement/kinetic, electric, light, sound, gravitational potential (GPE), - , thermal/heat, streatch/elastic potential energy (EPE)

no device transfers energy with 100% efficiency. some energy is always wasted, maily a heat that dissapates into the environment

we calculate the efficiency by:

efficiency = (useful energy out/total energy in) x100

e.g

100J electric energy → lightbulb → 70J heat

                                                    → 30J light

30/100 x100            this lightbulb is 30% efficient