GCSE Physics Tutorial: Calculating Energy Stored or Released when Temperature Changes
In physics, understanding the energy stored or released when the temperature of a substance changes is crucial for analysing thermal processes and their effects. This concept is especially relevant in understanding heat transfer, phase changes, and thermodynamics. Let's explore how to calculate the energy stored or released during temperature changes and examine some important related formulas and examples.
1. Specific Heat Capacity (c): Specific heat capacity (c) is a fundamental property of a substance, representing the amount of energy required to change the temperature of 1 kilogram of the substance by 1 degree Celsius (or 1 Kelvin). Specific heat capacity is measured in joules per kilogram per degree Celsius (J/kg°C) or joules per kilogram per Kelvin (J/kgK).
2. Energy Change Formula: The formula to calculate the energy change (Q) when the temperature of a substance changes is:
$Q = m \times c \times ΔT$
Where:
Q is the energy change in Joules (J).
m is the mass of the substance in kilograms (kg).
c is the specific heat capacity of the substance in J/kg°C or J/kgK.
ΔT is the change in temperature in degrees Celsius (°C) or Kelvin (K).
3. Energy Change Calculation Examples:
Example 1: Calculate the energy required to raise the temperature of 2 kg of water by 10 degrees Celsius. (Specific heat capacity of water is approximately 4200 J/kg°C).
Solution: Q = 2 kg * 4200 J/kg°C * 10°C Q = 84,000 Joules (J)
Example 2: Determine the energy released when 5 kg of iron cools down by 50 degrees Celsius. (Specific heat capacity of iron is approximately 450 J/kg°C).
Solution: Q = 5 kg * 450 J/kg°C * (-50°C) [Note: The change in temperature is negative as the iron cools down] Q = -112,500 Joules (J)
4. Phase Change Energy: During a phase change (e.g., solid to liquid or liquid to gas), there is no change in temperature even though energy is being added or released. The energy required or released during a phase change can be calculated using the formula:
$Q = m \times L$
Where:
L is the specific latent heat of the substance in J/kg. It represents the amount of energy required to change the phase of 1 kilogram of the substance at a constant temperature.
5. Applications: Calculating energy changes during temperature variations is essential in various real-world applications, including:
Designing heating and cooling systems for buildings and industries.
Understanding the energy required to change the state of matter during processes like boiling, melting, or condensation.
Analysing heat transfer in engines and machines.
6. Safety Considerations: Understanding energy changes during temperature variations is important in ensuring the safe operation of heating and cooling systems. Proper insulation and regulation of energy transfer help prevent accidents and overheating.
Conclusion: Calculating energy stored or released when temperature changes is a fundamental concept in GCSE Physics. The formula $Q = m \times c \times ΔT$ allows us to quantify the energy involved in temperature variations. Additionally, the formula $Q = m \times L$ helps us understand energy changes during phase transitions. This knowledge is not only essential for academic purposes but also has practical applications in various technological and scientific fields.
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