topic 1 - energy and resources

energy stores-

• energy is nevr used up, only transferred between stores and objects 
• energy stores: therma, kinetic, gravitational potential, elastic potential, chemical, magnetic, electrostatic and nuclear
• systems: an object or group of objects
• when a system changes, energy is transferred into or away from the system
• closed systems means no energy can enter or leave - total energy=0
• energy can be transferred through heating
• eg boiling water in a kettle - system
• enrgy from water> kettles heater> waters thermal energy store
• electrical> thermal> heating> thermal

workdone-

• work done is anoter way of saying energy transferred
• work is done when a current flows 
• falling objects such as a ball transfer energy 
• gravitational fall does the work
• GPE> kinetic energy 
• in real life the air resistance causes some energy to be movd into other stores such as thermal energy stores

kinetic and potential energy stores-

• anything moving is kinetic 
• the greater an objects mass, the fatser it travels, the more energy there is in the kinetic store 
• kinetic energy (Ek) = 1/2 x mass (m) x speed2 (v)
• lifting objects in a gravitational field requires work casuing an energy transfer to GPE 
• the higfher the object the more energy transferred 
• GPE = mass x GFS x height 
• stretching or squashing an object transfer energy to its elastic potential energy store 
• EPE = 1/2 x spring constant x extension2

specific heat capacity-

• more energy needs to be transferred to thermal energy stores than other to increase their temperatures 
• change in thermal energy = mass x specific heat capacity x change in temperature 
• practical- 
• measure mass of metal block 
• wrap it in an insulating material 
• insert themometer and heater into metal block 
• measure the initial temp and turn on power supply 
• start stopwatch
• as block heats uo, measure temp at every minute 
• turn off power supply 
• find the materials specific heat capacity 
• repeat with differnt insulators to test which is best 

conservation of energy and power-

• energy can be stored or dissipated never created or destroyed 
• dissipated is wasted energy (stored in unuseful ways)
• power…