Specific Heat Capacity | Physics for GCSE/IGCSE - Year 11 PDF Download

Internal Energy

• A rise in temperature increases the internal energy of an object. This rise can be attributed to the increase in the average speed of its particles, which in turn boosts their kinetic energy.
• Internal energy, essentially, signifies the total energy contained within a system, originating from the motion and positions of its constituent particles.
• Motion and Kinetic Energy: Motion of particles influences their kinetic energy. When particles move, they possess energy associated with their motion. For instance, a speeding car has high kinetic energy due to its motion.
• Positions and Potential Energy: The arrangement of particles relative to each other impacts their potential energy. Consider a stretched spring - it stores potential energy because of the positions of its particles. When released, this energy is converted into kinetic energy.
• Internal Energy Composition: Internal energy, comprising both kinetic and potential energies, characterizes the total energy within a system. It is the sum of the energies resulting from particle motion and positions relative to each other.

Average Kinetic Energy

• When a system is heated, it alters the substance's internal energy by elevating the kinetic energy of its particles.
• Consequently, the material's temperature correlates with the average kinetic energy of its molecules.
• This augmentation in kinetic energy (and internal energy) can:
  • Result in a rise in the system's temperature.
  • Induce a change of state, such as solid to liquid or liquid to gas.

Specific Heat Capacity

• The extent to which the temperature of a system increases is influenced by:
  • The mass of the substance undergoing heating.
  • The type of material involved.
  • The quantity of thermal energy transferred into the system.
• The specific heat capacity, denoted as "c," of a substance is described as:
  • The energy needed to raise the temperature of 1 kg of the substance by 1 °C.
• Various substances possess distinct specific heat capacities.
  • A substance with a low specific heat capacity heats up and cools down rapidly, meaning it requires less energy to alter its temperature.
  • Conversely, a substance with a high specific heat capacity heats up and cools down slowly, necessitating more energy to change its temperature.

Calculating Specific Heat Capacity

• The amount of energy needed to raise the temperature of a given mass by a given amount can be calculated using the equation:
  
• Where:
  • Δ E = change in thermal energy, in joules (J)
  • m = mass, in kilograms (kg)
  • c = specific heat capacity, in joules per kilogram per degree Celsius (J/kg °C)
  • Δ θ = change in temperature, in degrees Celsius (°C)