last minute physics

Question 1

why could wind not meet the UK’s energy demands

Answer 1

wind is unreliable
don’t turn when wind is too weak
not enough turbines

Question 2

Explain how oiling would affect the efficiency of the wind turbine

Answer 2

the proportion of NRG usefully transferred would increase
bc less work done against friction

Question 3

Explain why people should be encouraged to use energy efficient electrical devices

Answer 3

more efficient devices waste less energy
minimise energy demand
and minimise environmental impact from fossil fuel electricity generation

Question 4

Describe a method the student could use to determine the density of the rock

Answer 4

measure mass using a balance / scales
* part fill a measuring cylinder with water and measure initial
volume
* place rock in water and measure final volume
* volume of rock = final volume − initial volume
* fill a displacement / eureka can with water level with spout
* place rock in water and collect displaced water
* measuring cylinder used to determine volume of displaced water
* volume of rock = volume of displaced water
*
* use mass and volume to calculate density
● use of: density = mass
volume

Question 5

what does direct potential difference mean

Answer 5

polarity does not change

Question 6

nuclear fusion is

Answer 6

the joining together of nuclei

Question 7

during nuclear fusion the total mass of the particles

Answer 7

decreases

Question 8

suggest reasons why models are tested

Answer 8

develop an understanding of the process
assess environmental impact
assess safety risks
setup cost is lower for small scale experiments
make adaptions to the process

Question 9

environmental impact of getting electirict y from fossil fuels [2]

Answer 9

releases co2, causes global warming

Question 10

precuations+otther things in electriicyt circuit experiments

Answer 10

ensure current is low to avoid temp increase
switch off between readings
plot graph
reverse measurements

Question 11

describe how an increasing temp would increase the student’s results (IV)

Answer 11

current+pd wouldn’t be directly proportional
IV graph would not be straight
bc resistance would increase

Question 12

give a reason why its better to use a digital ammeter

Answer 12

no parallax error

Question 13

the students only took a measurement once
why can it not be used to show the method gives precise readings?

Answer 13

repeat readings need taking to show that the readings are close together

Question 14

its unlikely that the electricity the UK needs can be generated by solar panels, why?

Answer 14

a really large area of land would need to be covered with solar panels due to low efficiency of the solar cells

Question 15

what is meant by “random nature of radioactive decay?”

Answer 15

can’t predict which nucleus will decay next

Question 16

explain how closing a switch in the second loop of a parralel circuit

Answer 16

current would be almost zero in the first loop
because the switch has effectively zero resistance

Question 17

why can the car+ race track be considered a closed system?

Answer 17

the total energy of the car and track is constant

Question 18

when the volume of gas inside the syringe increased the pressure on the walls decreased , why?

Answer 18

more time between collisions of particles and the walls of the syringe so less average force on the walls
and pressure is total force per unit area

Question 19

explain the advantage of transmitting energy at a high PD

Answer 19

high PD means low currents
so less thermal NRg transferred to surroundings
increases efficiency of power transmission

Question 20

the child could recieve a fatal electric shock if the kite was near to but not touching a power cable

Answer 20

elec field strength v. high
so air becomes ionised
kite string conducts charge to person/earth

Question 21

which end of the diagram cell is positive

Answer 21

long one

Question 22

what is a zero error?

Answer 22

ammeter displays a reading when not connected

Question 23

why did cells put the wrong way into a torch not work

Answer 23

there is no current in a diode in the reverse direction because diode has very high resistance in the reverse direction

Question 24

two environmental advantaes of using gas not coal

Answer 24

no sulfur dioxide released so no acid rain
no particulates released so no global dimming
gas mining less destructive

Question 25

manmade sources of background radiation

Answer 25

medical xrays
radiotherapy
nuclear weapons testing
named nuclear disaster

Question 26

name nuclear fuels

Answer 26

plutonium + uranium

Question 27

how does nuclear fusion lead to energy release

Answer 27

lighter nuclei join to form heavier nuclei
some of the mass of the nuclei is converted to energy