physics energy

Question 1

what is a circuit

Answer 1

path for electricity

Question 2

what is ohms law

Answer 2

v=IxR

Question 2

equation for kinetic energy

Answer 2

Ek=1/2xmxv^2

Question 3

equation for gravitational potential energy

Answer 3

Ep=mxgxh

Question 4

equation for elastic potential energy

Answer 4

Ee=1/2xkxe^2

Question 5

equation for work done

Answer 5

w=fxd

Question 6

equation for power

Answer 6

p=e/t

Question 7

one equation for power

Answer 7

power= energy transferred / time

Question 7

define specific heat capacity

Answer 7

the amount of energy required to raise the temperature of one kilogram of a substance by one degree celcius

Question 8

define power

Answer 8

the rate at which work is done/ energy is transferred

Question 8

units used in specific heat capacity

Answer 8

kg/degrees celcius/joules

Question 9

another equation for power

Answer 9

power=work done/ time

Question 10

what is the unit for power

Answer 10

watts (W)

Question 11

explain the energy transfers when a ball is projected upwards

Answer 11

upwards= kinetic to gravitational potential
peak = maximum gravitational , zero kinetic

Question 12

explain the energy transfers for a bungee jumper

Answer 12

when falling = gravitational turns to kinetic
as the cord tightens= kinetic turns to elastic potential
at it lowest = the intial gravitational equals the elastic stored in the cord

Question 13

explain why a bungee jumper slows down when the cord begins to stretch

Answer 13

kinetic energy is converted to elastic
and as the kinetic energy decreases so does the velocity

Question 14

examples of chemical energy stores

Answer 14

food
fuel(wood, coal, petrol)
batteries

Question 15

4 different stores of energy

Answer 15

kinetic
gravitational
elastic
chemical

Question 16

law of conservation of energy

Answer 16

energy cannot be created or destroyed ( it can only be transferred )

Question 17

state any changes in the total energy of a ball that is kicked , assuming that no external forces act

Answer 17

the total energy of the system remains constant due to the conservation of energy

Question 17

what is waste energy

Answer 17

the energy that is not used for its desired purpose

Question 18

describe the energy changes that occur in a filament bulb

Answer 18

electrical energy is transferred into heat and light energy
light is a useful energy form heat is wasted energy

Question 19

one equation for calculating efficiency

Answer 19

= useful power output /total power output

Question 19

how can the efficiency of a system be increased

Answer 19

1.reducing waste output
2.recycling waste output

Question 20

state the consequence for energy transfer of a material with a high thermal conductivity

Answer 20

the rate of energy transfer through the material is higher than for a material with a lower thermal conductivity

Question 21

do double-glazed windows have a higher or lower thermal conductivity than single-glazed windows

Answer 21

lower meaning less energy transfers through them

Question 22

what key factors affect the cooling of a building

Answer 22

thickness of the walls the thermal conductivity of the walls

Question 23

three methods of reducing heat loss in a building

Answer 23

double glazing loft and wall insulation thicker walls

Question 24

how can the efficiency of a mechanical machine with moving parts be improved

Answer 24

lubricate any moving parts to reduce the friction and therefore energy loss due to heating

Question 25

how can the efficiency of a radiator be improved

Answer 25

installing metal foil sheets behind the radiator to reflect the heat back into the room rather than it being absorbed into the wall

Question 26

how can the efficiency of boiling water in a pan be improved

Answer 26

by placing a lid on the pan to reduce the heat loss from the top

Question 27

define a renewable energy source

Answer 27

an energy source which can be replenished as it is being used up

Question 28

four examples of renewable energy sources

Answer 28

wind hydro-electricity tidal solar

Question 29

example of a non-renewable energy resource

Answer 29

fossil fuels ( coal, oil and gas )

Question 30

what are the advantages of generating power using gas rather than coal

Answer 30

flexible generation ( can be switched off / on more easily )

Question 31

state two disadvantages of using renewable energy sources

Answer 31

1. supply is uncertain 2. generating power through other means is often more efficient

Question 32

environmental impacts of burning fossil fuels

Answer 32

carbon dioxide contributes to climate change sulphur dioxide leads to acid rain/ damaging crops

Question 33

state three advantages of fossil fuels as an energy resource

Answer 33

1. reliable 2. can produce large quantities of energy 3. cost- effective

Question 34

three advantages of nuclear power

Answer 34

1. large amounts of energy for relatively small quantities of fuel 2. does not contribute to climate change 3. low fuel costs

Question 35

three disadvantages of nuclear power

Answer 35

1. produces nuclear waste which is harmful 2. non renewable energy source 3. risk of nuclear accidents which have fatal consequences of humans and the environment

Question 36

how does hydroelectric power produce energy

Answer 36

rainwater collects behind a dam