energy

Question 1

what is the waste energy normally

Answer 1

heat

Question 2

what is the following for a car:

energy input
useful energy
waste energy

Answer 2

input= chemical

useful= kinetic

waste= heat and sound

Question 3

what is the following for a lamp:

energy input
useful energy
waste energy

Answer 3

input- electrical
useful- light
waste- heat

Question 4

what’s a sankey diagram

Answer 4

diagram to summarise electrical transfers taking place

Question 5

can energy be created or destroyed

Answer 5

no it can be stored, dissipated or transferred usefully

called conversion of energy

Question 6

how to work out the waste energy from a sankey diagram

Answer 6

useful energy- total energy

Question 7

what happens to waste energy

Answer 7

heat energy flows away from a hotter object to its cooler surroundings

Question 8

what is the efficiency

Answer 8

the proportion of energy supplied

transferred in useful ways

Question 9

how to calculate effientcy

Answer 9

efficiency= useful energy out/ total energy out

Question 10

what is useful energy

Answer 10

energy transmitted to where it is wanted, in the form it is wanted

Question 11

what is wasted energy

Answer 11

energy that isn’t usefully transmitted

Question 12

what energy spreads out into its surroundings

Answer 12

useful

wasted

and it becomes less useful as it spreads out, may heat up surrounding air

Question 13

what is weight measured in

Answer 13

newtons

Question 14

what is energy measured in

Answer 14

joules

Question 15

why do machines waste energy

Answer 15

1. friction between moving parts
2. wires get hot
3. air resistance
4. sound created by machinery

Question 16

what happens to surroundings when useful and wasteful energy is transferred

Answer 16

surroundings become warmer

Question 17

name a problem with energy as it dissipates (spreads out)

Answer 17

it gets more and more difficult to use for further energy transfers

Question 18

name some different forms of energy

Answer 18

1. chemical energy (fuel)
2. kinetic energy (moving)
3. Gravity potential energy
4. elastic potential energy
5. electrical energy

Question 19

can energy change from one form to another

Answer 19

yes eg

chemical energy in battery turns into electrical energy which turns into light energy which turns into energy heating surroundings

Question 20

what happens to an objects gravitational potential energy and kinetic energy when it falls

Answer 20

when when an object falls and gains speed
its gravitational potential energy decreases
and it’s Kinetic energy increases

Question 21

what is the conservation of energy

Answer 21

result meaning energy cannot be created or destroyed

conservation of energy applies to all energy changes

Question 22

how can you make machines more efficient

Answer 22

reduce

friction
air resistance
electrical resistance
noise

Question 23

can a machine be more than 100% efficient

Answer 23

no a machine can’t get more energy out that is put into it

Question 24

what 3 ways can hear be transferred by

Answer 24

1. radiation
2. conduction
3. convection

Question 25

what is heat radiation

Answer 25

the transfer of heat energy by infrared radiation

Question 26

what form of energy is coal

Answer 26

chemical

Question 27

how is chemical energy in food transferred into someone lifting a bar

Answer 27

chemical in porridge > kinetic in muscles> kinetic in moving bar