Work Done by Forces: The energy transferred mechanically is calculated as the product of the force applied and the distance moved in the direction of the force: .
Thermal Energy Change: When a substance changes temperature without changing state, the energy change is determined by its mass (), specific heat capacity (), and temperature change (): .
Specific Heat Capacity: This is a material property defined as the energy required to raise the temperature of kg of a substance by .
Identify the System: Always start by defining what objects are included in your system to track energy flow accurately.
Check Units: Ensure mass is in kilograms () and temperature change is in degrees Celsius () before using the thermal energy formula.
Conservation Principle: Remember that the total energy before a change must equal the total energy after the change (). If energy seems 'lost', it has likely been dissipated as heat.
Pathway vs. Store: A common mistake is confusing a pathway (like 'heating') with a store (like 'thermal energy'). Use 'heating' to describe the process and 'thermal store' to describe the state.
Energy Consumption: Students often say energy is 'used up' or 'lost'. In physics, energy is only ever transferred or transformed; it cannot be destroyed.
Temperature vs. Heat: Heat is the energy in transit (pathway), while temperature is a measure of the average kinetic energy of particles in a store. They are related but not identical.
Ignoring Friction: In mechanical systems, friction almost always causes some energy to be transferred to the thermal store of the surfaces and surroundings.
