(4.2-4.5) Energy: transfers, stores and principle

What is a system?

An object or group of objects

How does energy transfer occur in systems?

When there is a change, energy is transferred.

Name the energy stores.

(norris knows cats get everything- even the milk)

Nuclear

Kinetic

Chemical

Gravitational Potential

Electric

Electrostatic

Thermal

Magnetic

What is kinetic energy store?

The energy in moving objects

What is gravitational potential energy store?

When lifted through a gravitational field, objects gain this energy.

What is elastic energy store?

Energy stored when objects are stretched, squashed or bent.

What is magnetic energy store?

Energy stored when magnetic material interact with each other.

What is electrostatic energy store?

Energy stored when objects with charge interact with each other.

What is chemical energy store?

The store of energy transferred during chemical reactions

What is nuclear energy store?

Store of energy released during nuclear reactions

What is thermal energy store?

The hotter an object, the more energy it has in this store.

What are the energy transfer pathways?

Mechanical

Electrical

Heating

Radiation

What is the mechanical working transfer pathway?

When a force acts on an object

What is the electrical working transfer pathway?

When a charge moves through a potential difference.

What is the heating by particles transfer pathway?

Energy transferred from a hotter object to a colder one.

What is the (heating by) radiation transfer pathway?

Energy transferred by electromagnetic waves.

What is the principle of conservation of energy?

Energy cannot be created or destroyed, only transferred from one store to another.

What does the conservation of energy mean for a closed system?

The energy in the system must remain constant.

How can energy be wasted?

If it is dissipated- lost to surroundings- it is described as wasted.

What is efficiency?

The ratio of the useful energy output from a system to its total energy output.

What is the formula for efficiency?

efficiency = (useful output/total output) * 100%

What are Sankey diagrams?

A representation of energy transfer showing outputs through splitting arrows to show the proportions.

What do the different features of a Sankey diagram represent?

this pic.