Sci. y2 Phy.2 (Energy)

• Work Done (J) = Force (N) x Distance (M)
• Force (N) = Work Done (J) / Distance (M)
• Distance (M) = Work Done (J) / Force (N)
• Power (W) = Energy (J) / Time (S)
• Energy (J) = Power (W) x Time (s)
• Time (S) = Energy (J) / Power (W)
• Energy is stored in foods and fuels.
• The amount of energy is measured in Joules
• When you are a sleep your body needs energy to keep you warm and breath
• Children need more energy than adults so they can grow stronger and bigger
• The law of conservation:

  • Energy can't be created nor destroyed
• Energy always gets transferred
• When coal gets burned, the energy from the chemical store gets transformed to a thermal store
• Energy stores:

  • Chemical: food, fuels, battery's
• Energy stores:

  • thermal: hot objects
• Energy stores:

  • kinetic: moving objects
• Energy stores:

  • gravitational potential: position in a gravitational field
• Energy stores:

  • elastic: stretching, squishing
• When energy is waisted, scientists say call it dissipated
• You measure temperature in degrees celcius using a thermometer
• temperature doesn't depend on the amount of material that you have, but on the amount of energy in the thermal store
• solids, liquids, and gases don't get hotter.

  its the particles that vibrate faster
• energy moves from hotter object to colder object until they are in equilibrium
• Energy in solids is transferred through conduction
• Energy transferres because the particles colide with each other, when they vibrate
• Energy in liquids and gases transfer by convection
• In convection hotter particles get less dense and move up.

  colder particles move down, where they get heated.

  This repeats until all particles are in equilibrium
• Hot things give out light as well as infrared radiation
• infrared radiation is also called thermal radiation or heat
• all objects give out radiation, but the type depens on temperature
• Infrared radiation doesn't need particles to transfer energy, it can travel through vacuums
• coal, oil, and gas are non renewable fuels, because they will run out.
• they are called fosil fuels, because it took millions of years to form
• wind is an example of a renewable resource, because it won't run out
• How does a thermal power station work:

  1. water gets boiled and becomes steam
  2. steam drives a turbine
  3. the turbine drives a generator
  4. energy gets generated
• Energy is measured in Joules
• Power is measured in Watts
• Power is the energy transfer per second
• You pay for the number of kWh that are transferred to your house
• You could safe money by using appliances with a lower power rating, or using them for less time