Lesson Notes By Weeks and Term v4 - SHS 2
HEAT
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HEAT
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Subject: Physics
Class: SHS 2
Term: 1st Term
Week: 13
Grade code: 2.2.1.LI.3
Strand code: 2
Sub-strand code: 1
Content standard code: 2.2.1.CS.1
Indicator code: 2.2.1.LI.3
Theme: ENERGY
Subtheme: HEAT
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This lesson explores a fundamental concept in thermal physics: how different materials absorb and release heat. We will focus on a practical method used in laboratories called the "Method of Mixtures" to measure a key property of materials known as specific heat capacity. Understanding this helps us explain everyday phenomena, from why a metallic spoon in hot soup gets hot much faster than the soup itself, to how our coastal areas in Ghana stay cooler than inland areas like Tamale. By learning this experimental procedure, we can quantify how materials interact with heat energy.
2.1 Specific Heat Capacity (c)
Imagine you have a block of iron and the same mass of water. If you supply the same amount of heat to both, you will notice that the temperature of the iron block increases much more rapidly than the temperature of the water. This is because they have different abilities to store heat energy.
Definition: The specific heat capacity (c) of a substance is the quantity of heat energy required to raise the temperature of a unit mass (1 kg) of that substance by one degree Celsius (1°C) or one Kelvin (1K). A substance with a high specific heat capacity (like water) needs a lot of energy to get hot, but it also stores that energy for a long time. A substance with a low specific heat capacity (like most metals) heats up very quickly but also cools down very quickly.
Formula: The heat energy (Q) absorbed or lost by a substance is given by: `Q = mcΔT` Where: `Q` = Quantity of heat energy (in Joules, J) `m` = mass of the substance (in kilograms, kg) `c` = specific heat capacity of the substance (in Joules per kilogram per Kelvin, J/kgK or Joules per kilogram per degree Celsius, J/kg°C) `ΔT` = change in temperature (in Kelvin, K or degrees Celsius, °C). `ΔT = Final Temperature - Initial Temperature`.