Physics Term 3

Question 1

What is power? Give the equation:

Answer 1

• Power: rate at which energy is transferred/work done
• unit: W (watts)
  
  • p=delta E/time taken (p=E/t)
  • p=work done/ time taken (p=W/t)

Question 2

What is work done? Give the equation:

Answer 2

• work done: used when force is used in moving object
• unit: J (joules)
  
  • workdone = force x distance (w=f*d)

Question 3

GPE and KE

Answer 3

• KE = 1/2mv2
• GPE = mgh
• GPE = KE

Question 4

What is the conservation of energy?

Answer 4

• energy cannot be created or destroyed, it can only be transferred (usefully) or stored.

Question 5

Energy efficiency

Answer 5

Energy efficiency = useful energy output/total energy input * 100%

Question 6

Name the types/forms of energy:

Answer 6

• kinetic energy: any moving object has this
• potential energy: when lift object up, have gpe
• chemical energy: fules (coal, petrol, gasoline)
• nuclear energy: similar to C.E
• electrical energy: contains electricity
• strain energy: when streatch/squash
• elastic energy
• light energy: when object hot, glows
• sound energy
• internal energy: when object is hot
• thermal(heat) energy - when object go hot to cool

Question 7

What are the 4 types of energy transfers?

Answer 7

• heat
• mechanical
• electrical
• radiation

Question 8

List the renewable resources:

Answer 8

• biomass: comes from dead animals and plants
• solar: comes from sun; collected in solar pannel
• wind: wind turbines used to generate electricity
• geothermal: heat found under earth’s surface -> cold water pumped out -> steam
• hydroelectric power: energy harnessed from movement of water through rivers
• tidal: movement through tides drive turbines
• wave: movement of seeawater in and out of cavity on shore compresses trapped air which drives turbine.

Question 9

List the non-renewable energy resources:

Answer 9

• biomass
• Fossil fuels: coal (plants), oil (animals), natural gas (methane)
• nuclear - fadioactive minerals