energy ✓

Question 1

what is energy measured in ?

Answer 1

Joules (J)

Question 2

what is power measured in ?

Answer 2

Watts (W)

Question 3

what are Watts equivalent to ?

Answer 3

Joules per second (J/s)

Question 4

can energy be created ?

Answer 4

no

Question 5

can energy be destroyed ?

Answer 5

no

Question 6

can energy be transformed ?

Answer 6

yes

Question 7

what can energy be transformed into ?

Answer 7

one form to another

Question 8

what is the process of energy being transformed from one form to another called ?

Answer 8

conservation of energy

Question 9

what are the 10 different energy types ?

Answer 9

magnetic
kinetic
heat 
light 
gravitational 
chemical 
sound 
elastic 
electrical 
nuclear

Question 10

what are the energy transfers for a light bulb ?

Answer 10

electrical → light + heat

Question 11

what are the energy transfers for a fan ?

Answer 11

electrical → kinetic + sound

Question 12

what are the energy transfers for a kettle ?

Answer 12

electrical → heat + sound

Question 13

what are the energy transfers for a iPad ?

Answer 13

chemical → light + sound → heat

Question 14

what is the useful energy made in a light bulb ?

Answer 14

light

Question 15

what is the useful energy made in a fan ?

Answer 15

kinetic

Question 16

what is the useful energy made in a kettle ?

Answer 16

heat

Question 17

what is the useful energy made in an iPad ?

Answer 17

light + sound

Question 18

what is the wasted energy made in a light bulb ?

Answer 18

heat

Question 19

what is the wasted energy made in a fan ?

Answer 19

sound

Question 20

what is the wasted energy made in a kettle ?

Answer 20

sound

Question 21

what is the wasted energy made in an iPad ?

Answer 21

heat

Question 22

what is the equation for efficiency ?

Answer 22

efficiency = useful energy output ÷ total energy input

Question 23

how do you make the fraction given in the equation for efficiency a percentage ?

Answer 23

times it by 100

Question 24

what is the equation for work done ?

Answer 24

work done = force X distance moved (in direction of the force)

Question 25

what does work done = ?

Answer 25

work done = energy transferred

Question 26

how can energy be transferred by conduction ?

Answer 26

- as material gets hotter, particles gain kinetic energy so vibrate more - hotter particles collide with colder ones and pass on their kinetic energy - when the kinetic energy of the colder particles increases the means their temperature has increased

Question 27

how can energy be transferred by convection in hot substances ?

Answer 27

- heat up - space between particles has been increased due to thermal expansion - density has decreased - density is lower than the surrounding fluid so hotter fluid will rise

Question 28

how can energy be transferred by convection in cold substances ?

Answer 28

- cool down - space between particles has decreased due to thermal expansion - density has increased - density is higher than the surrounding fluid so colder fluid will sink

Question 29

how can energy be transferred by infra red radiation ?

Answer 29

- infra red radiation is absorbed by surfaces causing a rise in temperature

Question 30

which colour does infra red radiation work best in (best emitter and absorber) ?

Answer 30

matte black

Question 31

which state does convection work worst in ?

Answer 31

solids and a vacuum because a vacuum has no particles and the particles in a solid are unable to move

Question 32

which colour does infra red radiation work worst in (worst emitter and absorber) ?

Answer 32

silver

Question 33

how do convection currents work ?

Answer 33

- radiator heats are, thermally expands, becomes less dense and rises - warm air rises there are less particles left behind cold air particles move in and take their place - warm air cools down, becomes less dense, sinks

Question 34

what is a conductor ?

Answer 34

a substance which passes on heat energy easily and quickly

Question 35

what is an insulator ?

Answer 35

a substance which takes a long time to pass on heat energy

Question 36

why does a saucepan have a metal bottom but a plastic handle ?

Answer 36

- metal bottom is a good conductor so it takes up the heat energy quickly and passes it on quickly heating up the food - plastic handle is a bad conductor but a good insulator so it takes longer for the handle to pass on the heat energy and get hot meaning the person cooking can hold the handle without getting burnt

Question 37

do metals tend to be thermal conductors or insulators ?

Answer 37

thermal conductor

Question 38

does plastic tend to be a thermal conductor or insulator ?

Answer 38

thermal insulator

Question 39

how does double glazing work ?

Answer 39

- gas or sometimes a vacuum is trapped between the panes of glass - gases are bad conductors so reduces heat loss by conduction

Question 40

how does a space blanket work ?

Answer 40

- blanket is shiny silver so radiation that tries to escape is reflected back

Question 41

what is the equation for gravitational potential energy ?

Answer 41

gravitational potential energy = mass x gravitational force constant x height

Question 42

what is the symbol equation for gravitational potential energy ?

Answer 42

Ep = mgh

Question 43

what is the equation for kinetic energy ?

Answer 43

kinetic energy = 1/2 x mass x velocity ²

Question 44

what is the symbol equation for kinetic energy ?

Answer 44

Ek = 1/2mv ²

Question 45

what is the equation for power ?

Answer 45

power = work done or energy transferred ÷ time taken

Question 46

what is power when relating to the work done ?

Answer 46

rate at which work is done

Question 47

what is power when relating to the energy transferred ?

Answer 47

it is the rate at which energy is transferred

Question 48

what is conservation of energy ?

Answer 48

energy cannot be created or destroyed only transformed into different types