b) Energy Transfers

State all energy stores?

Kinetic

Gravitational

Chemical

Electrical

Magnetic

Electrostatic

Nuclear

Thermal

Describe mechanical energy transfer?

When a force acts on an object.

E.g Pulling, pushing

Describe electrical energy transfer?

A charge moving through a current.

Describe heating enenrgy transfer?

Energy is transferred from a hotter object to a colder one.

Describe radiation energy transfer?

Energy transferred by electromagnetic waves.

State conservation of energy?

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

Define efficiency?

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

Relationship between efficiency and enenrgy transferred?

High efficiency means most energy transferred its useful.

Low efficiency means most energy energy transferred is wasted.

What is thermal conduction?

Method of transferring energy in solids.

How thermal conduction occurs?

Happens when two solids of different temperatures come into contact so energy is transferred from hotter to cooler object.

Energy is transferred by vibration of atoms

What is thermal convection?

Method of energy transfer in liquids and gases.

How thermal convection occurs?

Heat source energy heats surrounding fluid particles.

These particles gain energy in their kinetic store and move further apart becoming less dense.

Since they’re further away from heat source particles cool and become denser so fall back down.

How does radiation transfer thermal enenrgy?

By infrared waves.

Explain role of convention in everyday events?

Distribute heat energy, such as in a radiator to heat whole room.

Relationship between temperature and radiation absorbed and emitted?

High temperature = more radiation absorbed and emitted.

Relationship between surface and radiation absorbed and emitted?

Dark, dull surface = more radiation absorbed and emitted.

Light, shiny surface = less radiation absorbed and emitted.

Method to investigate thermal energy transfer by conduction?

1. Attach ball bearing to metal strips using wax.

2. Turn strips upside down and heat centre using Bunsen burner.

3. When heat is conducted along to ball bearing wax will melt and ball with drop.

4. Time how long it takes for each strip’s balls to drop.

5. Repeat experiment to find average.

Method to investigate thermal energy transfer by convection?

1. Fill beaker with cold water and place on tripod.

2. Pick up crystals using forceps and drop into centre of beaker.

3. Heat beaker using bunsen beaker and record observations.

4. Repeat experiment with hot water and record observations.

Method to investigate thermal energy transfer by Radiation?

1. Set up four identical flaks painted in different colours: black, grey, white, silver.

2. Fill flasks with hot water .

3. Note starting temperature, then measure temperatures at regular intervals.

Explain ways of reducing unwanted energy transfer?

Reducing conduction: use materials with low thermal conductivity.

Reducing convection: fluid that forms currents must be prevented from moving.

Insulation: cavity wall insulation