Grade 8 Science - Forces and Energy

Vocabulary flashcards covering key concepts related to forces, energy, density, heat, temperature, and heat transfer.

Density

A measure of a material's or object's compactness. A ratio of mass to volume.

Planet Density

The density of a planet increases towards the centre. Average density can be found by dividing the total mass by the total volume.

Float or Sink?

If an object is less dense than water, it floats. If an object is more dense than water, it sinks. Whether an object sinks or floats depends mainly on density and buoyancy.

Heat Transfer

The main processes are conduction, convection, and radiation. It always moves from hot to cold, flowing when there's a temperature difference.

Temperature Scale

A range of numbers for measuring the level of hotness. Measured in degrees Celsius.

Heat

Total thermal energy in an object, the total energy of all the particles; unit is Joule.

Temperature

Average energy of the particles in an object; unit is Kelvin Celsius, Reamur, Fahrenheit.

Conservation of Energy

Energy cannot be created or destroyed, only transformed from one form to another. The total energy in the universe remains constant.

Energy

Measured in joules (J); examples include kilojoule (kJ), megajoule (MJ), and electron volts (eV).

Sankey Diagram

A diagram to show the flow of energy through a device or process.

Efficiency

amount of useful energy / total energy supplied to the device

Dissipation

When thermal energy moves from a hotter place to a colder place, it has dissipated, spreading out and moving to a colder place.

Conduction

Works best in solids; does not work well in liquids or gases; cannot happen in a vacuum.

Conductor

A material which allows electricity, heat, or sound to flow through it by allowing for charge transfer through the free movement of electrons.

Insulator

A material that doesn't easily allow energy to flow; examples include wood, plastic, and rubber.

Convection

Occurs when a cooler, denser mass of gas or liquid replaces a warmer, less dense mass of gas or liquid by pushing it upward.

Convection and Density

Lighter, warm material rises while heavier, cooler material sinks, creating circulation patterns in the atmosphere, water, and the Earth's mantle.

Radiation

Energy is released as particles or waves to transfer heat; it can be in the form of heat, sound, or light and can be conducted through empty space.

Application of Radiation: Vacuum Flasks

Plastic caps and double-walled glass containers with silvered surfaces are used for insulation.

Application of Radiation: Solar Panels

Electromagnetic radiation from the sun is captured and turned into useful forms of energy, such as heat and electricity, using various technologies.