AQA GCSE FOUNDATION PHYSICS - Specific Heat Capacity Calculations

AQA GCSE Foundation Physics: Specific Heat Capacity Calculations

This tutorial will guide you through calculating changes in thermal energy using the specific heat capacity formula.

Understanding Specific Heat Capacity

• Specific heat capacity is a measure of how much energy is needed to raise the temperature of 1 kg of a substance by 1°C.
• Units:
  • Specific heat capacity (c): Joules per kilogram per degree Celsius (J/kg°C)
  • Mass (m): Kilograms (kg)
  • Temperature change (?T): Degrees Celsius (°C)
  • Change in thermal energy (?E): Joules (J)

The Formula

The relationship between these quantities is represented by the formula:

?E = m * c * ?T

Where:

• ?E is the change in thermal energy (in Joules)
• m is the mass of the substance (in kilograms)
• c is the specific heat capacity of the substance (in J/kg°C)
• ?T is the change in temperature (in degrees Celsius)

Example Calculation

Question: A 500g block of copper is heated from 20°C to 60°C. Calculate the change in thermal energy. (Specific heat capacity of copper = 385 J/kg°C)

Solution:

1. Convert mass to kilograms: 500g = 0.5 kg
2. Calculate the temperature change: ?T = 60°C - 20°C = 40°C
3. Apply the formula: ?E = m * c * ?T ?E = 0.5 kg * 385 J/kg°C * 40°C ?E = 7700 J

Answer: The change in thermal energy of the copper block is 7700 J.

Tips for Solving Problems

• Always ensure your units are consistent.
• When calculating ?T, subtract the initial temperature from the final temperature.
• Remember to identify the correct specific heat capacity for the substance involved.
• Use the formula to solve for the unknown variable based on the information provided.

Practice Problems

1. A 2 kg block of aluminum is heated from 15°C to 55°C. Calculate the change in thermal energy. (Specific heat capacity of aluminum = 900 J/kg°C)
2. A 1.5 kg iron bar absorbs 3000 J of energy. If the initial temperature was 25°C, what is the final temperature? (Specific heat capacity of iron = 450 J/kg°C)
3. A 100 g copper pan is heated from 20°C to 100°C. How much energy is required? (Specific heat capacity of copper = 385 J/kg°C)

By practicing these calculations, you will gain a deeper understanding of specific heat capacity and its importance in thermal energy transfer.