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TOPIC 6 : TEMPERATURE & HEAT
TemperatureIt is a measure of degree of hotness , physical
quantity, measured using thermometer.SI unit is kelvin (absolute
temperature scale where zero Kelvin is absolute zero, equivalent
to-273 C ; 0C = 273 K )
0C = ( 0 + 273) K (273.15 accurately)example : 27 C = (27 + 273)
K = 300K
HeatThe energy that transfers from a body to another due to
temperature difference. This isthermal energy. SI unit is
Joule.
Heat TransferHeat can be transferred between objects by 3 ways:
conduction, covection and radiation; froma high-temperature body to
a low-temperature body.
ConductionProcess of heat transfer from high temperature to
lower temperature objects, in solid medium.Means of heat transfer
in solids, from atom to atom within a subtance.[ metals tend to
feel cold? You feel colder because metal conduct heat energy away
from yourhand, you perceive the heat that is leaving your hand as
cold ! ]
ConvectionMovement of gas from a hot area to colder area.
Warmer/hot gas molecules move upwardsand colder gas moves
downwards. Heat transfer in liquid and gasses, example: boiling
waterFree convection : Gravity and buoyancy forces cause the
movement of fluid.Forces convection : Means such as stirrer, is
used to move the fluid.
RadiationForm of heat transfer in light, through wave or ray,
either visible or not visible, example :~ heat from the sun to the
earth through space; the energy travels through nothingness !
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TUTORIAL 6
1. Define a) Temperature
b) Heat
2. State 3 ways of heat transfer.
3. Calculate the heat quantity needed to increase 2 kg of copper
from 20 C to 85 C.(Given: specific heat capacity of copper = 0.35
KJ/kg C )
4. How much heat does 30g of aluminium gives off as it cools
from 120 C to 60 C ?( Given: C aluminium = 880J/kg C )
5. A 100g silver spoon at 20 C is used to mix tea at 95 C. After
a few moment, the spoon
and tea achieved 88 C. If the mass of the tea is 300g,
a) Calculate the thermal absorbed by spoon.
b) Determine the specific thermal capacity for tea.(Given :
specific heat capacity of silver spoon = 0.23 KJ/kg C)
