Heat And Specific Heat

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Heat And Specific Heat
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Heat

• Energy that is transferred from one body to
  another because of temperature
• Unit
• 1 calorie (cal) heat needed to raise 1g
  water 1C
• Mechanical Equivalent of Heat amount of work
  done by 1 calorie
• 1 cal 4.186 J

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Example

• A 60 kg person overeats by 500 Calories. How much
  work must he do to make up for this binge?
• How high of a flight of stairs would this be?

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Example

• A 3.0g bullet traveling at 400m/s passes through
  a tree and slows to 200m/s. How much heat is
  produced?

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Specific Heat

• Amount of heat (Q) required to change the temp of
  a material is proportional to the mass(m) and the
  temp change
• Q cm?T
• c specific heat
• higher specific heat, more heat it takes to
  change the substances temp

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Example

• How much heat is required to raise the temp of an
  empty 20kg vat made of iron from 10C to 90C?
• What if the vat is filled with 20kg of water as
  well?

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Calorimetry

• Process of determining heat
• Works off the idea that heat lost by one material
  must be gained by another

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Example

• A 15.0 g sample of metal at 75oC is added to
  150.0g of water at 15oC. The temperature of the
  water rises to 18.3oC. Calculate the specific
  heat of the metal.

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Example

• If 200ml of tea at 95C is poured into a 150g
  glass cup at 25C, what will be the final temp of
  the mixture?

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Example

• A .150kg sample of metal is heated to 540C and
  then placed in 400g of water at 10C which is in
  a 200g aluminum calorimeter. The final temp of
  the mix is 30.5C. What is the specific heat of
  the metal?