OCR Gateway GCSE Physics: P8

Give the typical speeds of wind and sound

Wind = 13m/s
Sound = 330m/s

Give the typical speeds of walking, cycling and running

Walking = 1m/s
Cycling = 7m/s
Running = 5m/s

What is the equation to calculate speed?

Speed = Distance / time

What is the unit of speed?

m/s

Define reaction time

The time from seeing/ hearing an event and starting to brake

What is the typical human reaction time?

0.2-0.5s

Describe how to measure reaction time

Another person holds a ruler above your hand at 0cm and drops it randomly.
The distance it has travelled is measured.
Use (final velocity- initial velocity) / acceleration = time to calculate reaction time

Describe thinking distance

The distance that a car travels while the driver reacts to a hazard

State the factors that affect thinking distance

Speed, alcohol, drugs, tiredness, age, distractions

Define braking distance

The distance a car travels whilst it is braking

State the factors that affect braking distance

Speed, brake quality, road surface, water on the road

Define total stopping distance

Thinking distance + Braking distance

State the factors that affect total stopping distance

Speed

Describe the relationship between thinking distance and speed

They are directly proportional

Describe the relationship between braking distance and speed

Braking distance is proportional to speed2

Explain why large decelerations are dangerous

Large forces are required to stop you. Seatbelts can injure you

Why are high speeds involved in large accelerations?

As you are stopped very quickly by large forces

Explain how a seatbelt works

The seatbelt stretches and exerts a force on you

State the 8 different types of energy resource

Biofuels, fossil fuels, hydroelectricity, wind, solar, geothermal, wave, tidal

Describe what is meant by a renewable energy resource

An energy source that will not run out (it is replaced faster than it is used)

Describe what is meant by a non-renewable energy resource

An energy resource that will run out. It is used faster than it is being made

Describe what a biofuel is

A fuel made from plants or waste

Give an advantage and disadvantage of biofuels

Uses a lot of land to grow them. They are carbon neutral

State which energy resources are renewable

Hydroelectricity, wind, tidal, solar, waves, geothermal

State which energy resources are non-renewable

Fossil fuels (coal, oil and gas), nuclear

What are the main uses and environmental impacts of coal?

Uses: Electricity generation, heating and some transport.

Impacts: Burning produces greenhouse gases (CO2) contributes to acid rain (SO2).

Benefit: Reliable output

What are the main uses and environmental impacts of oil?

Uses: Transport and Heating

Environmental impacts: Burning produces greenhouse gases (CO2) and contributes to acid rain. Serious environmental damage if split

Benefits: Reliable output. Provides a compact source of energy for transport.

What are the main uses and environmental impacts of gas?

Uses: Electricity generation, heating and some transport

Benefits: Reliable output

Impacts: Burning produces greenhouse gases CO2 but not acid rain

What are the main uses and environmental impacts of nuclear energy?

Uses: Electricity generation and some military transport

Impacts: Produces The waste but no other emissions.

Negatives: Costly to build and decommission

Benefits: Reliable output

How do fossil fuels cause global warming?

Produce carbon dipxide which reflects infra-red radiation back towards earth and traps it

Describe how wind is used to generate electricity

Large fan blades that are connected to generators. When it's windy, the blade and generator turn

Describe how hydroelectricity can be used to generate electricity

A dam is built on a river. Water flows through the dam, turning turbines connected to generators

Describe how tides can be used to generate electricity

Large fan blades connected to generators are in the sea on the coast. As the tide moves in and out, these blades spin

Describe how the Sun can be used to generate electricity

Light -> electricity by photovoltaic cells/ solar cells

State the advantages and disadvantages of using wind to generate electricity

Free fuel, no greenhouse gases, renewable. Energy generated depends on wind speed, take up a lot of room

State the advantages and disadvantages of using tides to generate electricity

No greenhouse gases made, renewable, free fuel. Can only be used in some areas, can affect wildlife

State the advantages and disadvantages of using the Sun to generate electricity

Renewable, free fuel, no greenhouse gases. Take up a lot of room, energy dependent on amount of sunlight, expensive to set up

Describe what a fossil fuel is

Coal, oil or gas. A fuel made from dead plants/ animals

Describe how fossil fuels are used to generate electricity

Burn the fuel to produce heat im a boiler. Heat water to make highly pressurised steam. Steam is used to turn blades in a turbine, which turns a generator. Generator produces electrical energy distributed to houses via national grid.

State the advantages and disadvantages of using fossil fuels to generate electricity

Convenient, releases a lot of energy. Non-renewable, makes greenhouse gases

Explain why our use of energy sources has changed over time

Population increase, new ways to produce electricity, more devices need electricity/ fuel

What do people need to consider when deciding what energy resource to use?

Set-up/ removal costs, environmental effects, contribution to climate change, life expectancy of sources

Describe what the national grid is

Power stations, wires and transformers used to supply electricity

Describe what transformers are

A component made of 2 coils and an iron core, which changes PD and current

Explain why we use the national grid

To reduce the current, preventing the wires from heating up. This will reduce costs, power losses and improve efficiency

Describe what the two types of transformer are

Step-up and Step-down

Describe what a step up transformer does

It increases the PD and decreases the current

Describe what a step down transformer does

It decreases the PD and increases the current

Describe the difference between direct and alternating PD

The PD is constantly changing and the PD is always the same value

Explain why there are several step-down transformers at the end of the national grid

To decrease the PD for factories and to decrease it further for homes

Describe the structure of a step-up transformer

The secondary coil has more turns than the primary coil

What is the PD and frequency of the UK domestic electricity supply?

230 Volts and 50Hz

What type of PD/ current is used by a battery?

Direct

What are the three wires in the plug of an appliance?

Live, neutral, Earth

What are the colours of each wire in a plug?

Live = Brown
Neutral = Blue
Earth = Yellow and Green

Describe what the live wire does

It has a high PD and carries the current to the appliance

Describe what the neutral wire does

It takes the electrons away from the appliance

Describe what the Earth wire does

It connects the casing to the Earth. If the live wire touches the outer casing, the current flows to Earth, preventing the user from getting a shock

Describe what happens if the live wire is lose in an appliance

It will make the appliance casing live (if made from a conductor). If it is earthed, the current will flow through the Earth wire, making it safe

Which appliances do not need an earth wire?

Ones with cases made from insulators. These are 'double insulated

What is the PD of each wire in a plug?

Live = 230V
Neutral = 0V
Earth = 0V

Explain why the live wire is dangerous

It has a high PD. So if you touch it, you will complete the circuit and get an electric shock

Describe the role of a fuse in a plug

When there is a current surge, it melts. Breaking the circuit

What material are electric plug pins made of?

brass

What can be used in a plug instead of a fuse?

Circuit Breakers- Break circuit when current is too high but resettable by a switch

Describe what red shift is

The apparent increase in the wavelength of light emitted from a source moving away from you

How can you measure the speed of galaxies?

Using the light we receive from them in their absorption spectra

What happens to the amount of red-shift a light source shows if it is moving faster?

It increases

Describe what blue-shift is

The apparent decrease in the wavelength of light emitted from a source moving towards you

Describe the relationship between the distance a galaxy is away from us and the speed it is moving away from us

The further the galaxy is away, the more red shift it shows as it is moving faster

What evidence do we have for the Universe expanding?

CMBR and Red-shift

What evidence do we have for the Big bang?

CMBR and Red-shift

Describe what is meant by the Big bang

The model of the beginning of the Universe, where space and time expanded from a singularity

Describe what CMBR is

Cosmic, Microwave, Background, Radiation. Radiation detected in all directions, which is evidence for the Big bang

Explain how CMBR provides evidence for the Big bang

The microwave radiation is left-over radiation from the Big bang. Gamma radiation that has been 'stretched' by the Universe expanding

Describe what a planet is

A large spherical object that orbits the Sun

Describe what a star is

A large ball of hot gas, that emits electromagnetic radiation through nuclear fusion

Describe what a minor planet is

A small object orbiting the Sun with other small objects/ rocks around it

Describe what a comet is

A lump of ice and rock that orbits the Sun

Describe what the asteroid belt is and where it is

A group of small rocks that orbit the Sun. There is one between Mars and Jupiter and one past Neptune

Describe what a moon is

A natural satellite that orbits a planet

Describe what an artificial satellite is

A man-made object that orbits a planet

Describe what a nebula is

A large cloud of dust and gas

Describe how a main sequence star forms

Dust and gas particles in a nebula attract each other. This causes the particles to heat up and they move faster. Eventually the particles move so fast, fusion starts

Describe the energy transformations as a star forms

GPE -> KE -> Heat

Describe the different stages in the lifecycle of a star similar to the Sun

Nebula -> Main sequence star -> Red giant -> White dwarf

Describe the different stages in the lifecycle of a star bigger than the Sun

Nebula -> Main sequence star -> Red supergiant -> Supernova -> Black hole or Neutron star

Describe what causes dust and gas to attract each other when a main sequence star forms

The gravity between each dust and gas particle

Describe how a star releases energy

Nuclear fusion. Mass is converted into energy

Explain why the size of a main sequence star through its life is constant (in equilibrium)

The inwards force of gravity is balanced with the outwards force of heat pressure

Explain what happens to a star when it runs out of hydrogen

The force of gravity pulling in is larger than the heat pressure pushing out as fusion has stopped. This causes the core to collapse and the outside layer move away

Describe what a geostationary satellite is

A satellite which is always over the same part of Earth. It takes 24hours for it to orbit

Describe what a polar satellite is

A satellite that orbits over the North and South poles

What keeps planets and satellites in orbit?

Gravity

What happens if the speed of a body's orbit increases?

Its orbital radius increases

Explain what happens to the speed of an orbiting body as it gets further away from another body?

It decreases, as the force of gravity decreases

What happens to the gravitational attraction of a body as you get further away from it?

It decreases

State the order of the planets, starting from closest to the Sun

Mercury, Venus, Earth, Mars Jupiter, Saturn, Uranus, Neptune

Describe some uses of a geostationary satellite

Communications, satellite TV

Describe some uses of a polar satellite

Military/ spying, observing Earth, weather