P8

Question 1

Why are large decelerations dangerous?

Answer 1

As force is equal to mass times Excel oration large decelerations require a large force.

Question 2

How can decelerations be reduced making them less dangerous?

Answer 2

By slowing the object down over a longer period of time for example seat belts and airbags, crumple zones and crushable foam in bike helmets and shinpads

Question 3

Stopping distance=

Answer 3

Stopping distance= thinking distance + braking distance

Question 4

What is the thinking distance?

Answer 4

Thinking distance is the distance the car travels during the drivers reaction time.

Question 5

What factors can affect the thinking distance?

Answer 5

Tiredness, alcohol, drugs, distractions and speed all affect the thinking distance

Question 6

What is the braking distance?

Answer 6

The braking distance is the distance taken to stop once the brakes are applied

Question 7

What factors affect the braking distance?

Answer 7

The braking distance is affected by speed, mass, condition of brakes and grip of tyres

Question 8

How can you measure reaction time?

Answer 8

1) Hold a ruler between someone’s thumb and forefinger so it hangs at zero
2) Drop it without warning
3) They should catch as quickly as possible
4) The longer the distance the longer the reaction time

Question 9

How can you calculate the thinking distance and braking distance on a velocity time graph?

Answer 9

The thinking distance is the area under the graph where the speed is increasing or steady and the braking distance is the area under the graph where the brakes are applied and speed decreases

Question 10

Explain how fossil fuels create non-renewable energy

Answer 10

1) Fossil fuels burn transferring energy from the chemical energy store to the thermal energy store of the water
2) The water from steam which turns a turbine transferring energy to kinetic energy store of the turbine
3) The turbine power is the generator which transfers the energy electrically away via the National Grid

Question 11

Explain how nuclear reactors create non-renewable energy?

Answer 11

1) The energy from nuclear fission is used to heat the water
2) The water turns to steam which turns a turbine
3) As the turbine revolves it drives the generator which transfers the energy electrically away to the National Grid

Question 12

What are some problems with non-renewable energy sources?

Answer 12

1) Fossil fuels really CO2 which contributes to global warming
2) coal and oil release sulphur dioxide which causes acid rain
3) Nuclear waste is dangerous and difficult to dispose of
4) Nuclear power carries the risk of major catastrophe

Question 13

What is a renewable energy source?

Answer 13

I renewable energy sources one will never run out

Question 14

What are biofuels

Answer 14

Biofuels are renewable energy source made from plants and waste that can be burnt to produce electricity or used to run cars.

Question 15

What are the advantages of biofuels?

Answer 15

Biofuels aren’t meant to have any net effectOn the level of CO2 in the atmosphere. They are also reliable as crops grow quickly.

Question 16

What are the disadvantages of biofuels?

Answer 16

They’re very expensive to make and to grow the crops need to make biofuels Takes up space needed to grow food and decreases biodiversity by clearing habitats by burning land to create space

Question 17

What is Windpower?

Answer 17

Wind power is a renewable energy source created by win turbines which have a generator powered by rotating blades turned by the wind. There is no pollution however they are noisy and can spoil the view

Question 18

What is solar power?

Answer 18

Solar power is created by solar cells which are made from special materials which release electrons when light falls on them generating an electric current. There is no pollution but they are more suitable for sunny countries and only work during the day

Question 19

What is hydroelectricity?

Answer 19

Hydro electricity is in renewable energy source created by dams. Rainwater is caught an allowed out through turbines which powers the generator creating electricity. However the dams can flood valleys which destroys habitats. Sure costs are high but there are minimal running costs

Question 20

What are tidal barrages?

Answer 20

Tidal barrages are big dams built across rivers where they meet streams to create renewable energy . When the tide comes in the water is left out through turbines at a set speed which powers the generator. There is no pollution however it can spoil the view and affect habitats

Question 21

What type of current does the UK mains electricity have?

Answer 21

Do UK mains electricity is an alternating-current produced by alternating voltage where the potential difference and current constantly change direction. It is at 50 Hz and around 230 V

Question 22

What type of current do batteries and cells have?

Answer 22

Batteries and cells have a direct covenant produced by a direct voltage

Question 23

What shows you whether occurrence is alternating or direct?

Answer 23

A cathode ray oscilloscope

Question 24

What Is the National Grid ?

Answer 24

the National Grid is a network of wires and transformers that transfers energy electrically from power stations to homes in industry .

Question 25

Potential difference across primary coil X current in primary coil =

Answer 25

Potential difference across primary coil X current in primary coil =potential difference across secondary coil X current in secondary coil

Question 26

What is the neutral wire for ?

Answer 26

The neutral wire is blue and it completes the circuit , electricity flows out of the neutral wire . It has no potential difference

Question 27

What is the livewire for?

Answer 27

The livewire is brown and it carries the voltage alternating current of about 230 V

Question 28

What is the earth wire for ?

Answer 28

The earth wire is green and yellow and is the safety it carries the current away if something goes wrong it has no potential difference

Question 29

What happens if something goes wrong in a plug ?

Answer 29

If the livewire touches the metal case the current will flow from the casing through the earth wire which has a low resistance increasing the current as current is equal to potential difference divided by resistance . This increased current melts the fuse which breaks the circuit and cuts off the live supply making it impossible to get an electric shock .

Question 30

What is a satellite in Geostationary orbit ?

Answer 30

Satellite with the Geo stationary orbit has a high orbit over the earth Equator the orbit once every 24 hours meaning they stay above the same point with the earths surface because they rotate with the earth

Question 31

Give some examples of uses of satellites in geostationary orbit

Answer 31

They are ideal for communications (telephone, TV and radio ) because they stay the same point above the Earth is it easy to point transmitters and receivers at them

Question 32

What is a satellite polar orbit ?

Answer 32

A satellite in polar orbit are much closer to the earth so they move much faster and orbit very quickly.

Question 33

Give examples of where polar orbits would be used

Answer 33

Weather , mapping and surveillance

Question 34

Why is red shift evidence for the universe is expanding ?

Answer 34

Redshifts – looking at light from distant galaxies there is an observed increase in the wavelength and decrease in the frequencies of light , the light has shifted towards the red end of the spectrum . This suggests all distant galaxies are moving away from us and more distant galaxies have greater redshifts the nearer ones which means more distant galaxies are moving away faster than nearer ones proving evidence universe is expanding

Question 35

Why is microwave radiation evidence that the universe is expanding ?

Answer 35

Cosmic microwave background radiation – is an observation by scientists which detected low-frequency microwave radiation is coming from all directions in all parts of the universe which is strong evidence for the big bang as this is the leftover energy from the initial explosion .

Question 36

What is the big bang ?

Answer 36

Initially all matter in the universe occupied a single point then it exploded space started expanding and the expansion is still going on .

Question 37

Explain the life-cycle of the star

Answer 37

1) the force due to gravity draws the gas and dust in the atmosphere together to form a protostar .
2) as the temperature rises the star gets denser and the particles collide more often when it gets high enough hydrogen nuclei undergoes nuclear fusion to form a helium nuclei. This gives that massive amounts of energy .
3) start enters a period of equilibrium becoming a main sequence star , the energy released by nuclear fusion that results in an outward pressure expanding the star is balanced by the force due to gravity pulling the star inwards . This lasts for billions of years
4) eventually the Hydrin in the core begins to run out and effusion of heavy elements occurs , the star swells up on the surface begins to cool turning it red into a red giant
5) when the red giant Manzel feel it becomes unstable and ejects its outer layer of dust dust and gas as a planetary nebula. Leaving behind a hot dense solid core known as a white dwarf
6) however some stars when they run out of fuel collapsing in themselves resulting in a massive explosion called a supernova .
7) the supernova throws the outer layers of dust and gas into space leaving a dense core: neutron star of the star is big enough it will become a blackhole .

Question 38

What is intensity of radiation?

Answer 38

Intensity is Power per-unit area

Question 39

How can you increase the intensity of the wavelength ?

Answer 39

To increase the intensity he must increase the temperature

Question 40

What are seismic waves ?

Answer 40

Seismic waves waves produced by earthquakes detected by seismometers

Question 41

What are the two types of seismic waves ?

Answer 41

P-waves – longitudinal waves that travel through solids and liquids faster than S-wave
S-wave – transverse waves the only travel in solids they travel slower than P waves