P8 Flashcards
How do you calculate reaction time
Thinking distance / Speed
State one precaution a person can use to get accurate results when dropping a ruler
Drop ruler from same height above hand.
How to calculate stopping distance?
Thinking distance + Braking distance
What are the factors that affect thinking distance?
Time - tiredness, drugs, alcohol
Speed - faster you go , further you’ll travel
What are the factors that affect braking distance?
Speed
Mass
Condition of brakes
Road conditions
when speed increases what happens to thinking and braking distance?
Thinking distance increases at same rate
Breaking distance and speed have a squared relationship.
Voltage is increased between transmission through the National Grid . How much would this increase in voltage affect the Current.
It will reduce current
as power = voltage * current
The National Grid transfers power from power stations to homes and factories. Describe one risk and one benefit of using high voltages to transmit electricity
Risk - potential electric shock/death
Benefit - reduces heat loss, more efficient.
Explain why radio waves may be produced by transmission lines.
AC produces oscillations which is type of radio wave.
Explain why it is more efficient to transfer energy at high voltages
Lower current, less energy wasted
Write one risk of living near a nuclear power station and explain how this risk is reduced.
Leak of nuclear waste. Can be reduced by using safer storage and methods of disposal
Describe the advantage of wind turbines compared to conventional coal power stations.
Supplies more sustainable energy compared to non renewable
No polluting waste is produced
The future demand for fossil fuels is expected to increase. Give two reasons why scientists are worried about this increase in demand.
Theres not much left - finite resource
Causes damage to environment , e.g. increase in greenhouse gases
Nuclear fission can be used as a power source to produce electricity. Give one advantage and disadvantage of using nuclear power to produce electricity.
Good - preserves fossil fuels
bad - produces a lot of nuclear waste
How do we know the universe is expanding
Red shift - light is shifted towards the red end of the spectrum
Suggests that all the distant galaxies are moving away from us very quickly.
Therefore universe is expanding
What does CMBR show
Cosmic Microwave Background Radiation
Scientists can detect low frequency microwave radiation coming from all direction and all parts of the universe.
Describe the Big Bang model
Big Bang model states that all the matter in the universe occupied a single point. The single point exploded (The Big Bang) causing the universe to start expanding.
State 2 pieces of evidence that support the Big Bang model
Red shift of light from distant galaxies
CMBR
What is the life cycle of stars
Stars first form clouds of dust and gas
Due to gravity they spiral and form a protostar
Fusion occurs to form helium nuclei and a main sequence star is formed
Eventually hydrogen in the core begins to run out and fusion of heavier elements occur so red giant and red super giant form.
Red giant - when it runs out of fuel it becomes unstable and ejects a nebula which leaves behind a white dwarf. this cools down and eventually fades away.
Red super giant - when it runs out of fuel they collapse in on themselves in a massive explosion - SUPERNOVA.
the exploding supernova leaves a dense core called neutron star.
If star is big enough it could leave a black hole - super dense point where light can’t escape.
