energy

Question 1

whats kinetic energy?

Answer 1

energy of a moving object

0.5xmassxvelocitysquared

Question 2

whats elastic potential energy?

Answer 2

amount of energy stored in a stretched spring

0.5xspring constantxextension squared

Question 3

whats gravitational energy?

Answer 3

massxgravityxheight

Question 4

how can a system be changed?

Answer 4

• heating
• workdone by forces
• workdone when a current flows

Question 5

thermal energy

Answer 5

change in thermal energy=massxspecifc heat capacity x temperature change

Question 6

whats the conservation of energy principle

Answer 6

energy can be transferred usefully, stored or dissipated but can never be created or destroyed

Question 7

whats power

Answer 7

the rate of doing work

p=energy transfered/time or p=workdone/time

Question 8

what are energy resources used for

Answer 8

• transport
• generating electricity
• heating

Question 9

what depends on what energy resources are chosen

Answer 9

reliability and environmental impact

Question 10

what are non renewable products

Answer 10

coal
oil
gas
nuclear fuel

Question 11

what are renewable products

Answer 11

bio fuel, wind,hydroelectricity,geothermal,water waves, sun

Question 12

whats efficiency

Answer 12

efficency=useful output energy transfer/total input energy transfer

an efficient device doesn’t waste energy, it transfers it to a useful energy store
an iffecent one dissipates most its energy

Question 13

how can energy transfers be improved

Answer 13

by reducing the dissipation of energy’s.g lubricating a device to reduce friction or using thermal insulation

Question 14

whats specific heat capacity

Answer 14

the amount of energy required to raise the temperature of 1kg of the substance by 1 degree

change in thermal energy/mass x temp change

Question 15

dissipated energy

Answer 15

wasted energy

Question 16

problems w required pracicle of specific heat capacity

Answer 16

thermal energy out in air -use insulater w blower thermal confuctivity

not all thermal energy passing into oil-ensure immersion is fully submerged

Question 17

whats a series circuit

Answer 17

currents the same way the whole way round,byt pd difference of the cell/batery is equal to the sum of the pd of components

Question 18

parallel circuits

Answer 18

each component independant .pd is the same across all components

Question 19

whats potential difference

Answer 19

needed for a current to flow
current x. resistance
power=current x resistance
charge=current x time

Question 20

what does the live wire do

Answer 20

carry current from supply to appliance

around 230v

Question 21

what the earth wire do

Answer 21

safety wire, stopping appliance becoming live.only carries current if there’s a fault

Question 22

what does the neutral wire do

Answer 22

complete the circuit by carrying current from the appliance back to the supply.close or at 0v

Question 23

ammeter

Answer 23

current of circuit

Question 24

voltmeter

Answer 24

p.d of circuit

Question 25

energy transferred

Answer 25

powerxtime

chargexpotential difference

Question 26

what are some things about solids

Answer 26

not very compressable
high density
definite volume
particles vibrate around a fixed position

Question 27

liquids

Answer 27

not very compressable
high density
definite volume
assumes shape of container
particles can move

Question 28

gas

Answer 28

highly compressible 
low density
fills container completley
assumes shape of container
particles move randomly

Question 29

density

Answer 29

mass/volume

Question 30

volume

Answer 30

lengxwidthxheight

Question 31

what does the increase temperature of a system depend on

Answer 31

mass of susbstance
energy input
type of material\

Question 32

alpha

Answer 32

2 protons 2 neutrons

Question 33

beta

Answer 33

high speed electron

Question 34

gamma

Answer 34

electromagnetic wave

Question 35

whats half life

Answer 35

half life of a radioactive isotope is the time it takes for the countrate from a sample of a radioactive isotope to half