Uploaded on

 

More in: Education
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Be the first to comment
    Be the first to like this
No Downloads

Views

Total Views
682
On Slideshare
0
From Embeds
0
Number of Embeds
0

Actions

Shares
Downloads
7
Comments
0
Likes
0

Embeds 0

No embeds

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
    No notes for slide

Transcript

  • 1. Energy
    ThermalEnergy
  • 2. Describe theenergytransfers in thefollowingitems
  • 3. Thermalenergy
    Temperature and heat are two different thing
    We use different units of measurement for these two things:
    Temperature is measured in _______
    Heat is measured in ________
  • 4. Whatisheat?
    Heat is a form of energy and is measured in Joules.
    Scientists use the word "thermal" to mean "heat".It does not matter whether you say "heat energy" or "thermal energy“ they both mean the same thing.
  • 5. Whatistemperature
    Temperature is a measure of how hot something isand is measured in °C (degree Celsius).
    Heat is related to temperature but the two are not the same.
  • 6. Differencebetweenheat and temperature
  • 7. Differencebetweenheat and temperature
    Imagine that you have a bucket full of water and a cup full of water both at 25 °C.
    If you add the same amount of heat energy (for example 50,000J) to both you would find that the temperature of the cup of water increases by much more than the temperature of the bucket of water.
  • 8. Thermalenergy
    To raise 2 different substances to the same heat, we need different amounts of heat energy
    For example:
    To heat 1kg of copper from 20°C to 21°C requires 390J,
    To heat 1kg of aluminium from 20 to 21°C takes 910J. This is known as the SPECIFIC HEAT CAPACITY of a substance.
  • 9. Specificheatcapacity
    The specific heat capacity of a substance is the amount of heat energy required to raise the temperature of the substance unit mass by a unit change in temperature.
    The unit mass is usually 1kg, while the unit change in temperature is 1K or 1°C. The key formula is:
    Energy = specific heat capacity × mass × change in temperature
  • 10. Specificheatcapacity
    Calculatethefollowing:
    How much energy is needed to increase the temperature of 500 g of lead from 20 ºC to 45 ºC? The specific heat capacity of lead is 128 J/kg/ºC.
  • 11. Heat transfer
    Heat is transferred naturally from a substance with a higher temperature to a substance with a lower temperature.
  • 12. Heat Transfer
    Complete the following definition using the words below:
    ___________ energy or heat is always transferred from a _________ place to a ___________ place. The amount of energy _____________ depends on how big the _______________ difference is
    cooler thermal transferred
    hotter temperature
  • 13. Heat transfer
    Draw arrows to show the direction of
    energy transfer:
  • 14. Heat transfer
    Heat can be transferred in three ways.
    Conduction - by a substance which does not move (solids).
    Convection - by  substance which moves (liquids and gasses).
    Radiation - infra-red radiation is exchanged between all substances.