Energy 2025 (Cambridge Ch 9)

A set of 40 Q&A flashcards covering key concepts from the energy chapter, including forms of energy, energy transfer and transformation, heat transfer, and energy sources.

What is energy?

The ability to do work; energy cannot be created or destroyed; total energy in the universe remains constant.

How are energy forms classified?

All energy is classified as either kinetic energy, potential energy, or a mixture of both.

What is Kinetic Energy (EK)?

The energy of moving matter.

What factors determine the amount of kinetic energy?

Mass and speed (velocity) of the object.

What is Potential Energy (EP)?

Energy stored due to height, stretch/compression, or chemical form.

Kinds of Kinetic Energies

Thermal, Wave, Sound, Light

Kinds of Potential Energies

Gravitational, Electrical, Elastic, Chemical, Nuclear

What is Gravitational Potential Energy (GPE)?

Energy stored when an object is above the ground; depends on mass, height, and gravity.

What is Electrical Potential Energy?

Energy stored in electrostatic situations (electric fields).

What is Chemical Potential Energy?

Energy stored in bonds between atoms; released when burnt or digested.

What is Elastic Potential Energy?

Energy stored when an elastic material is stretched or compressed.

What is Nuclear Energy?

Energy stored in unstable atomic nuclei; released in nuclear reactions (non-renewable).

What is Thermal Energy?

Energy contained within a material that is responsible for its temperature.

What is Wave Energy?

Energy carried by a travelling wave or standing wave.

What is Sound Energy?

Energy of vibrating air; transferred through a medium as a wave and heard as sound.

What is Light Energy?

Visible light; electromagnetic energy from the sun, lamps, fires, or bioluminescence.

What are common sources that provide Thermal Energy?

Sun, flames, chemical reactions, electrical devices, people/animals, and friction.

What is Energy Transfer?

Energy passed from one object to another.

What is Energy Transformation?

Energy changes from one form to another.

What is the Law of Conservation of Energy?

Energy cannot be created or destroyed; only transformed; total energy remains constant.

What is an energy flow diagram?

A diagram showing inputs (left) and outputs (right) for a machine, illustrating energy flows and transformations.

What is useful energy?

Energy that is intentionally used or produced.

What is wasted energy?

Energy produced as a by-product and not used; often becomes heat.

What is energy efficiency?

A measure of how effectively input energy is converted into useful energy (useful energy out ÷ energy in).

Direction of heat flow between two objects of different temperatures?

From the hotter object to the cooler object until equilibrium is reached.

What are the three modes of heat transfer?

Conduction, convection, and radiation.

What is a conductor?

A material that allows heat to flow easily; all metals are conductors.

What is an insulator?

A material that slows heat transfer; examples include socks, blankets, roof insulation.

What is the relationship between volume and thermal energy?

Thermal energy depends on temperature, mass and material—volume alone does not determine it.

Name three renewable energy sources.

Wind, solar, and hydro (also geothermal and biomass as additional examples).

What are the risks of nuclear energy?

Risk of meltdown and disposal of nuclear waste.