4 - Energy

Question 1

What are the 8 energy stores?

Answer 1

Chemical potential
Kinetic
Gravitational potential 
Thermal
Elastic potential 
Nuclear
Magnetic 
Electrostatic

Question 2

What is efficiency ?

Answer 2

The ratio of the useful energy output to the total energy input expressed as a percentage

Question 3

How do you calculate efficiency?

Answer 3

EFFICIENCY = USEFUL ENERGY OUTPUT
———————————-
TOTAL ENERGY OUTPUT
X 100

Question 4

What are sankey diagrams used to show?

Answer 4

Energy transfers

Question 5

In a sankey diagram, the WIDTH OF THE ARROW = …?

Answer 5

AMOUNT OF ENERGY

Question 6

What does the beginning of the arrow of a sankey diagram represent?

Answer 6

The total energy input

Question 7

What do the arrows going off at the end of a sankey diagram represent?

Answer 7

The energy output

Question 8

In a sankey diagram where is the…

1) useful energy arrow
2) wasted energy arrow

Answer 8

1) at the top

2) at the bottom

Question 9

What is the method of thermal energy transfer in solids?

Answer 9

Conduction

Question 10

What is the method of thermal energy transfer in liquids and gases?

Answer 10

Convection

Question 11

Describe the 3 steps to conduction

Answer 11

1) the particles in the solid, closer to the heat source vibrate and move with a larger amplitude
2) they then transfer the energy by colliding with the next particles and passing the vibrations on.
3) the collisions continue to the end of the solid, until all particles are moving with a large amplitude and the solid is heated

Question 12

Why does conduction occur faster in metals?

Answer 12

Metals have delocalised electrons which move in Brownian motion and cause extra collisions

Question 13

Describe the 3 steps to convection

Answer 13

1) the particles gain energy and move faster and collide with eachother more.
2) this means that they then move further apart and become less dense than the particles above.
3) therefore they rise up, and cooler, denser particles move down to take their place. This process continues until all of the liquid/gas is heated up. (This is called a convection current)

Question 14

Why can’t convection happen in solids?

Answer 14

Because the particles are in - situ and can’t move

Question 15

What is infrared radiation?

Answer 15

The process in which thermal energy is transferred by an infrared wave that carries energy and can travel through a vacuum

Question 16

Which surfaces are good emitters and absorbers but bad reflectors?

Answer 16

Matte black

Question 17

Which surfaces are good reflectors but bad emitters and absorbers

Answer 17

Shiny/silver

Question 18

Why do insulators reduce heat movement?

Answer 18

Because their have large air spaces between their particles, limiting vibrations being passed on

Question 19

What are the 5 energy transfers?

Answer 19

mechanically 
Electrically 
By heating 
By radiation 
By a chemical reaction

Question 20

What is a good way to remember the energy stores?

Answer 20

My 
English 
Teacher 
Gives
Katie 
Notes 
Every
Class

Question 21

What does My English Teacher Gives Katie Notes Every Class stand for?

Answer 21

Magnetic 
Electrostatic 
Thermal
Gravitational potential 
Kinetic 
Nuclear
Elastic potential 
Chemical potential