Cambridge IGCSE Physics Energy Stores and Transfers

What is energy?

Energy is the quantity that must be changed or transferred to make something.

How is energy measured?

Energy is a scalar quantity measured in joules (J).

What are energy stores?

Energy stores are systems where energy is transferred during events and processes.

What is Kinetic Energy?

Kinetic energy is the energy store of a moving object.

How does speed affect Kinetic Energy?

As the speed of an object increases, its kinetic energy increases.

What is the equation for Kinetic Energy?

The equation is $E_k = \frac{1}{2}mv^2$ where E_k is kinetic energy (J), m is mass (kg), and v is speed (m/s).

What is Gravitational Potential Energy (GPE)?

GPE is the energy store of an object raised against the force of gravity.

How does height affect GPE?

The higher an object is raised, the greater its gravitational potential energy.

What is the equation for change in GPE?

The equation is $\Delta E_p = mg\Delta h$ where \Delta E_p is change in gravitational potential energy (J), m is mass (kg), g is gravitational field strength (N/kg), and \Delta h is change in height (m).

What is Chemical Energy?

Chemical energy is stored in chemical bonds and can be released during chemical reactions.

Examples of Chemical Energy

Food, muscles, batteries, fuels are all examples of chemical energy.

What is Nuclear Energy?

Nuclear energy is the energy stored in the nucleus of an atom.

What happens in a nuclear power station?

Nuclear energy stored in uranium is released to produce electricity.

What is Elastic (Strain) Energy?

Elastic energy is stored when an object is stretched or compressed elastically.

What happens when the stretching force is removed from an elastic object?

The object returns to its original shape when the stretching or compressing force is removed.

What is Internal Energy?

Internal energy is the total kinetic and potential energy of all the particles in an object.

How does heating an object affect its internal energy?

Heating an object increases its internal energy.

Difference between Internal Energy and Thermal Energy

Internal energy is stored energy, while thermal energy is energy being transferred due to temperature differences.

Ways energy can be transferred

Energy can be transferred by mechanical working, heating, radiation, electrical working, and sound.

Four ways energy is transferred

1. Mechanical Working (Force) 2. Heating (Thermal Working) 3. Radiation 4. Electrical Current

What is the Principle of Conservation of Energy?

It states that energy cannot be created or destroyed, only transferred between energy stores.

What is efficiency in energy transfer?

Efficiency is the fraction or percentage of the input energy that is usefully transferred.

Common causes of wasted energy

Most wasted energy is dissipated as thermal and sound energy due to heat from burning fuels and friction.

Reasons to use energy resources efficiently

Energy should be used efficiently because it is expensive, supplies are often limited, and production can harm the environment.