Energy Transfers (8k)

Question 1

What is the equation for power?

Answer 1

Power = energy/time

Question 2

What is the equation for efficiency?

Answer 2

Efficiency= useful energy transferred/ total energy applied x 100%

Question 3

How do you work out payback time?

Answer 3

_____________________cost of change
payback time = ___________________
savings per year

Question 4

Define evaporate

Answer 4

When a liquid turns into gas

Question 5

Define joule (J)

Answer 5

A unit for measuring energy.

Question 6

How many joules are in a kilojoule

Answer 6

There are 1000 joules in a kilojoule

Question 7

Define kilowatt (kW)

Answer 7

A unit for measuring power. There are 1000 watts (W) in 1 kilowatt (kW).

Question 8

How many watts are in a kilowatt?

Answer 8

There are 1000 watts (W) in 1 kilowatt (kW).

Question 9

Define internal energy

Answer 9

The energy stored in the movement of particles. Sometimes called thermal energy.

Question 10

Define conduction

Answer 10

The way energy is transferred through solids by heating

Question 11

Explain conduction

Answer 11

Conduction takes place in solids and can also happen in liquids (although not very well).
The particles in a solid are held together tightly. When they gain energy they vibrate faster and further, and the vibrations are passed on. Metals are the best conductors. Most other solids are poor conductors.

Question 12

Define convection

Answer 12

The way energy is transferred by heating in fluids/liquids

Question 13

Define convection current

Answer 13

A flow of liquid or gas caused by part of it being heated or cooled more than the rest

Question 14

Define Infrared radiation

Answer 14

A way of transferring energy by heating that does not need a medium (material). Infrared radiation can travel through transparent things and a vacuum (empty space).

Question 15

Define thermal conductor

Answer 15

A material that allows internal (thermal) energy to be transferred through it easily.

Question 16

Define thermal insulator

Answer 16

A material that does not allow internal (thermal) energy to be transferred through it easily

Question 17

Define accurate

Answer 17

A measurement that is close to the true value.

Question 18

Define precise

Answer 18

Measurements that are close to one another but not as close to the correct value

Question 19

Define random error

Answer 19

An error that can be different for every reading

Question 20

Define efficiency

Answer 20

A way of saying how much energy something wastes

Question 21

Define power rating

Answer 21

The number of joules of energy an appliance uses every second

Question 22

Define Sankey diagram

Answer 22

A diagram showing energy transfers, where the width of each arrow is proportional to the amount of energy it represents.

Question 23

Define kilowatt-hour (kWh) and how many kilojoules is it equal to?

Answer 23

The amount of energy used by a 1 kilowatt (kW) appliance in one hour. It is equal to 3600 kilojoules (kJ).

Question 24

Define payback time

Answer 24

The time it takes to get back (in energy savings) the money you spent on making an energy-saving change.