last minute physics Flashcards
why could wind not meet the UK’s energy demands
wind is unreliable
don’t turn when wind is too weak
not enough turbines
Explain how oiling would affect the efficiency of the wind turbine
the proportion of NRG usefully transferred would increase
bc less work done against friction
Explain why people should be encouraged to use energy efficient electrical devices
more efficient devices waste less energy
minimise energy demand
and minimise environmental impact from fossil fuel electricity generation
Describe a method the student could use to determine the density of the rock
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
what does direct potential difference mean
polarity does not change
nuclear fusion is
the joining together of nuclei
during nuclear fusion the total mass of the particles
decreases
suggest reasons why models are tested
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
environmental impact of getting electirict y from fossil fuels [2]
releases co2, causes global warming
precuations+otther things in electriicyt circuit experiments
ensure current is low to avoid temp increase
switch off between readings
plot graph
reverse measurements
describe how an increasing temp would increase the student’s results (IV)
current+pd wouldn’t be directly proportional
IV graph would not be straight
bc resistance would increase
give a reason why its better to use a digital ammeter
no parallax error
the students only took a measurement once
why can it not be used to show the method gives precise readings?
repeat readings need taking to show that the readings are close together
its unlikely that the electricity the UK needs can be generated by solar panels, why?
a really large area of land would need to be covered with solar panels due to low efficiency of the solar cells
what is meant by “random nature of radioactive decay?”
can’t predict which nucleus will decay next
explain how closing a switch in the second loop of a parralel circuit
current would be almost zero in the first loop
because the switch has effectively zero resistance
why can the car+ race track be considered a closed system?
the total energy of the car and track is constant
when the volume of gas inside the syringe increased the pressure on the walls decreased , why?
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
explain the advantage of transmitting energy at a high PD
high PD means low currents
so less thermal NRg transferred to surroundings
increases efficiency of power transmission
the child could recieve a fatal electric shock if the kite was near to but not touching a power cable
elec field strength v. high
so air becomes ionised
kite string conducts charge to person/earth
which end of the diagram cell is positive
long one
what is a zero error?
ammeter displays a reading when not connected
why did cells put the wrong way into a torch not work
there is no current in a diode in the reverse direction because diode has very high resistance in the reverse direction
two environmental advantaes of using gas not coal
no sulfur dioxide released so no acid rain
no particulates released so no global dimming
gas mining less destructive
manmade sources of background radiation
medical xrays
radiotherapy
nuclear weapons testing
named nuclear disaster
name nuclear fuels
plutonium + uranium
how does nuclear fusion lead to energy release
lighter nuclei join to form heavier nuclei
some of the mass of the nuclei is converted to energy
