Energy Stores And Transfers

Question 1

What are the 8 types of energy stores?

Answer 1

• kinetic
• thermal
• chemical
• gravitational potential
• elastic potential
• electrostatic
• magnetic
• nuclear

Question 2

What is the rule about energy?

Answer 2

No energy can be lost or gained. Energy can be stored, transferred and dissipated but it can never be created or destroyed. The total energy in a closed system has no net change.

Question 3

What are the four main ways energy can be transferred?

Answer 3

• mechanically > a force acting on an object
• electrically > a charge doing work against a resistance
• by heating > energy transferred from a hotter object to a colder object
• by radiation > energy transferred by waves

Question 4

What is efficiency?

Answer 4

It is

Question 5

What makes energy useful?

Answer 5

Energy is only useful when it has transferred from one store to another useful store. Some of the input energy is dissipated (lost) to other in-useful stores. The more efficient the device is the less energy is wasted.

Question 6

What are the two ways to reduce dissipation?

Answer 6

• lubrication > when an object moves their is usually one frictional force opposing it, this reduces friction and limits the thermal energy that friction radiates away
• insulation > having insulation reduces the thermal conductivity preventing more energy dissipating.

Question 7

How to draw a Sankey diagram?

Answer 7

You firstly scale up the total energy and then the wasted energy splits off vertically downwards, the useful energy continues forward.