How is speed calculated and what are the standard units? 3 marks Stimulating Challenging Innovative Exciting Nurturing Creative Engaging John O’Gaunt Science

How is speed calculated and what are the standard units?

3 marks

Stimulating Challenging Innovative Exciting Nurturing Creative EngagingJohn O’Gaunt Science Team 2013 (Produced by Mr P Scutt)

How is speed calculated and what are the standard units?

- Distance- Divided by time- m/s

How is acceleration calculated and what are the standard units?

3 marks


How is acceleration calculated and what are the standard units?

- Change in velocity - Divided by time taken- m/s2

What is the difference between speed and velocity?

2 marks


What is the difference between speed and velocity?

- Speed is how fast you are going. - Velocity is how fast you are going in

a particular direction

What can be shown on a distance time graph?

5 marks


What can be shown on a distance time graph?

- Gradient = speed (distance/time)- Flat section = stationary (not change

in distance)- Steeper gradient = faster- Downhill sections = going back to

starting position- Curves = acceleration

What can be shown on a velocity-time graph?

7 marks


What can be shown on a velocity-time graph?

- Gradient = acceleration- Flat sections = steady speed- Steeper = greater acceleration- Uphill = acceleration- Downhill = deceleration- Area under graph = distance

travelled - Curve – changing acceleration

What is the difference between mass and weight?

4 marks


What is the difference between mass and weight?

- Mass is the amount of stuff an object is made of.

- Mass is measured in kilograms (Kg)- Weight is caused by the pull of

gravity.- Weight is measured in Newtons (N)

How are mass and weight related and what are the units?

3 marks


How are mass and weight related?

- Weight = mass x gravitational field strength

- Weight – Newtons (N), Mass – Kilograms (kg)

- Gravitational field strength = N/Kg

How do balanced forces affect the motion of an object?

3 marks


How do balanced forces affect the motion of an object?

- No change in velocity- Stationary objects remain stationary- Objects that are moving, remain at

constant speed.

How do unbalanced forces affect the motion of an object?

2 marks


How do unbalanced forces affect the motion of an object?

- Causes acceleration - Or deceleration

What affects the size of a resultant force?

3 marks


What affects the size of a resultant force?

- Force = mass- X- Acceleration

Or (F = ma)

What is meant by terminal velocity?

5 marks


What is meant by terminal velocity?

- Objects in free-fall- Initially accelerate- Resistance slows them down- Until reach a constant maximum

speed- Where resistance forces =

accelerating forces.

What affects the stopping distance of a car and how is it calculated?

9 marks


What affects the stopping distance of a car and how is it calculated?

- Thinking distance is affected by- speed and- How dopey you are

- Braking distance is affected by - Wear and tear of brakes and tyres- Weather- Condition of road- How heavy the vehicle is- How fast the vehicle is travelling

What is work done and how is it calculated?

4 marks


What is work done and how is it calculated?

- Work is energy transferred- Work is the force need to move an

object a distance- Calculated by work done = force x

distance- Work is energy transferred and so

units are Joules.

What is weight and how is it calculated?

3 marks


What is weight and how is it calculated?

- Weight = mass x gravitational field strength

- The force by which the mass of the object is pulled down to earth

- Measured in Newtons (N)

What are the difference and similarities between kinetic and potential energy?

7 marks


What are the difference and similarities between kinetic and potential energy?

- Both are forms of energy- Kinetic is movement energy- Kinetic energy = ½ x mass x velocity2

- Potential is a store of energy- Potential energy can be elastic

potential or - Gravitational potential energy- Both are measured in joules (J)

How do you calculate momentum and what are the units?

4 marks


How do you calculate momentum and what are the units?

- Mass x velocity- Kg m/s- Momentum before = momentum

after- Momentum is conserved when no

external forces act.

How do you calculate the force acting on an object that causes a change in momentum?

3 marks


How do you calculate the force acting on an object that causes a change in momentum?

- Force (N) = change in momentum (kg m/s)time taken for change (s)

How do crumple zones help to reduce the impact on a person?

3 marks


How do crumple zones help to reduce the impact on a person?

- They increase the time taken for the car to stop.

- The longer it takes for a change in momentum

- The smaller the force on the person.

What can help to reduce the impact on a person in a car crash?

3 marks


What can help to reduce the impact on a person in a car crash?

- Crumple zones- Seat belts- Air bags

What is gravitational potential energy and how is it calculated?

3 marks


What is gravitational potential energy and how is it calculated?

The energy stored in an object because if its position above the Earth

Energy = mass x gravitational field strength x height

Energy – Joules (J)Mass – Kilograms (kg)Gravitational field = N/kgHeight = metres (m)

What is kinetic energy and how is it calculated?

3 marks


What is kinetic energy and how is it calculated?

Another name for movement energy

Energy = 0.5 x mass x velocity x velocity

Mass – Kilograms (kg)Velocity = metres per second, (m/s)Energy = Joules (J)

What causes static electricity?

3 marks


What causes static electricity?

- Rubbing materials together- Causes electrons- To move from one material to

another- The material which loses electrons

becomes positively charged. - The material that gains electrons

becomes negatively charged.

Why does a van de graff generate a spark?

3 marks


Why does a van de graff generate a spark?

- Electrons build up on the dome- As more electrons build up, the

potential difference increases. - When the potential difference is big

enough, a spark can be produced.

Where is static electricity helpful?

2 marks


Where is static electricity helpful?

- In smoke precipitators on chimneys which attract dust particles.

- In photocopiers

Where is static electricity a problem?

2 marks


Where is static electricity a problem?

- Lightening - Petrol pump at petrol station – could

cause an explosion.

What is meant by current?

2 marks


What is meant by current?

- The flow of electrons - Measure in amps

What is meant by voltage?

2 marks


What is meant by voltage?

- The driving force that pushes current round.

- Measured in volts

What is meant by resistance?

2 marks


What is meant by resistance?

- Anything that slows down the flow of current

- Measured in ohms, Ω

What happens when you increase voltage?

1 mark


What happens when you increase voltage?

- More current will flow

How is an ammeter used and what does it show?

4 marks


How is an ammeter used and what does it show?

- Measures the current- In amps - Must be placed in series - Can be placed anywhere in the

circuit

How is an voltmeter used and what does it show?

4 marks


How is an voltmeter used and what does it show?

- Measures the voltage - In volts- Must be placed in parallel- Must be placed across a component

(proper name is potential difference)

What does a voltage-current graph look like for a resistor, at constant temperature, and why?

4 marks


What does a voltage-current graph look like for a resistor, at constant temperature, and why?

High Temp

Low Temp

Cur

rent

Potential Difference

• Straight line – therefore directly proportional, so an ohmic resistor at constant temperature.

• Resistance decreases as temperature increases

What does a voltage-current graph look like for a filament lamp and why?

6 marks


What does a voltage-current graph look like for a filament lamp and why?

• Curve – therefore not directly proportional, so not an ohmic resistor.

• Resistance increases as current increases

• Caused by increase in temperature as current increases.

• Increase in temperature causes particles to move more in the wire.

• Reversing the current has not effect – they are a mirror image.

What does a voltage-current graph look like for a diode and why?

4 marks


What does a voltage-current graph look like for a diode and why?

• Only works in ONE direction

• No a straight line – so not an ohmic conductor.

• Reverse direction, the current is negliable.

What are the circuit symbols for:

- Cell- Battery- Switch- Filament lamp- Fuse- Fixed resistor

- Variable resistor- Dioide- Thermistor


What are the circuit symbols for:Cell – push electrons around the circuit

Battery – consists of 2 or more cells Switch – enables

current to be switched on or off

Lamp – emits light

Diode – only allows current in ONE DIRECTION ONLY.

Fixed resistor – limits current flowing in a circuit

Variable resistor – varies current flowing in a circuit

Fuse – a wire that melt when current is TOO high.

Thermistor – reacts to changes in temperature

What does a voltage-current graph look like for a thermistor and why?

4 marks


Thermistor

High Temp

Low Temp

Cur

rent

Potential Difference

• Straight line – therefore directly proportional, so an ohmic resistor at constant temperature.

• Resistance decreases as temperature increases

What does a voltage-current graph look like for a thermistor and why?

What are the key features of a series circuit?

4 marks


What are the key features of a series circuit?

- Current only has one route to flow- Current is the same at all locations- Potential difference is shared

between components- Resistance is calculated by adding all

of the resistances for the components together.

What are the key features of a parallel circuit?

4 marks


What are the key features of a parallel circuit?

- Current only more than one route to flow

- Current shared between the different branches

- Potential difference is the same across all components

- Resistance depends on the components resistance.

Give an example of a series circuit and a parallel circuit.

2 marks


Give an example of a series circuit and a parallel circuit.

- Series = torch, Christmas fairy lights- Parallel = components in a car (fan,

lights, wipers etc).

What is the difference between a.c. and d.c. and where are they used?

7 marks


What is the difference between a.c. and d.c. and where are they used?

a.c. - Alternating current- The current switches direction - Used in mains electricity - Mains is set at 50Hz

d.c.- Direct current- Current flows in one direction only- Used by batteries

What wires are found in a plug and how are they connected?

6 marks


What wires are found in a plug and how are they connected?

- yellow/green- Earth

- Brown - Live

- Blue- Neutral

How do fuses work?

5 marks


How do fuses work?

- Fuses are pieces of wire- When current is too high, the wires

melt- As the wires get hotter as current

increases.- The thicker the wire the more current

it can withstand without melting. - Prevent surges of electricity

How does earthing work?

3 marks


How does earthing work?

- If a fault develops where a live wire touches the metal case

- the large current - Flows through the earth wire

How is the power rating on an electrical item calculated?

3 marks


How is the power rating on an electrical item calculated?

Power = Voltage x Current

Or

Power = Energy/Time

What is meant by charge and how is it calculated?

3 marks


What is meant by charge and how is it calculated?

- Current is the flow of electrical charge (in Coulombs, C) around a circuit.

- When current flows for a length of time then charge (Q) can be calculated:

- Charge = Current x Time

How is the energy transferred in a circuit calculated?

3 marks


How is the energy transferred in a circuit calculated?

Energy transferred = Charge x potential difference

What did Rutherford find out?

3 marks


What did Rutherford find out?

- He came up with the nuclear model of the atom.

- In the centre is a nucleus- Where mass is concentrated- Made up of protons and neutrons- Around the outside is empty space- With electrons whizzing around- Electrons have a negligible mass.

What is meant by an isotope?

2 marks


What is meant by an isotope?

- An element with the same number of protons

- But a different number of neutrons

What are the three radioactive decay methods and what is the difference between them?

14 marks


What are the three radioactive decay methods and what is the difference between them?

- Alpha- Is a helium nuclei (mass of 4, charge +2)- Heavy, does not travel far (low penetration)- Strongly ionising – knock electrons off other atoms when collide.

- Beta- Is an electron (no mass, charge 1-)- Quite fast moving - Small- Moderately penetrating, - Moderately ionising

- Gamma- Is a photon (no mass, no charge)- Penetrate a long way- Weakly ionising – pass through rather than collide with atoms.

What is the difference between nuclear fission and fusion?

11 marks


What is the difference between nuclear fission and fusion?

Fusion- The fusing (joining) of small nuclei- Form a larger nuclei- Releases a lot of energy (happens in stars)- Only happens at extremely high temperatures- Contained in a magnetic field as materials would just vaporise under

high heat.

Fission- Splitting heavy nuclei in to smaller ones- Used in nuclear power stations and submarines- Heat used to heat water to drive turbine- Fuel is uranium and plutonium - Results in radioactive waste- Causes a chain reaction

What are the stages of nuclear fission?

8 marks


What are the stages of nuclear fission?

Fission – the splitting of the atomUsing a neutronWhich collides with an atom and causes it to split. On splitting, the atom releases two more neutrons which collide with other atoms and cause them to split too. This causes a chain reaction. Releasing lots of energy. This is how the atomic bomb works. The fuel is usually enriched uranium

What does a nuclear reactor need to control the reaction?

8 marks


What does a nuclear reactor need to control the reaction?

- Control rods – absorb surplus neutrons

- Coolant – to transfer heat from the reaction to the heat exchanger

- Thick steel walls to withstand the high temperatures

- Thick concrete to stop the radioactivity escaping

What happens in nuclear fusion?

9 marks


What happens in nuclear fusion?

- The joining of nuclei- E.g. hydrogen- 2 Protons collide, producing heavy hydrogen- 2 more protons collide, producing- Heavier nuclei- Two heavier nuclei collide to produce - e.g. helium - Happens in the Sun (contains a core of

plasma where atoms have no electrons)- Releases massive amounts of energy

How has the model of the atom changed?

5 marks


How has the model of the atom changed?

Plum pudding model:- All the charged particles are randomly spread

throughout the atom – like raisins in a sponge pudding.

New Model:- Nucleus contains protons and neutrons- Nucleus contains most of the mass of the atom.- Electrons are found in shells around the nucleus- Electrons are held in place by electrostatic

charges.

What do the two numbers with an element tell you?

5 marks


What do the two numbers with an element tell you?

Mass Number (the bigger number)The total number of protons AND neutrons.

Atomic Number (the smaller number)The number of protons in the atomIn an uncharged atom, also the number of electrons.

What is Half Life?

2 marks


What is Half Life?

The time taken for a radioactive COUNT RATE to decrease by HALF.

Or

The time taken for the number of radioactive nuclei to halve.

What affects Half Life?

2 marks


What affects Half Life?

Nothing

It is a completely RANDOM event.

How is the penetration of each type of radioactivity different?

3 marks


How is the penetration of each type of radioactivity different?

Alpha – Low as stopped by air/paper

Beta – Medium as stopped by metal

Gamma – High – stopped only by thick lead or concrete.

How can the type of radioactivity be shown using an electric field?

3 marks


How can the type of radioactivity be shown using an electric field?

If pass through an electric field:Alpha – As positively charged (Helium Nuclei), it is attracted towards the negative terminal.

Beta – As negatively charged (electron) it is attracted towards the positive electrode)

Gamma – As it is uncharged and has no mass it is unaffected and so passes through without any change.

How can the type of radioactivity be shown using an magnetic field?

3 marks


How can the type of radioactivity be shown using an magnetic field?

If pass through an electric field:Alpha – Deflected slightly. As it has a greater mass than Beta, it isn't deflected as much.

Beta – Deflected in the opposite direction to Alpha and by more as it is lighter.

Gamma – Passes through without any change.

Why is ionisation dangerous?

3 marks


Why is ionisation dangerous?

As radioactivity pass through, it can knock electrons off of atoms – causing ions to be produced.

X-rays cause ionisation and can damage and kill cells.

Alpha is the most dangerous inside the body as it has a greater ionising effect.

Where is radioactivity useful?

5 marks


Where is radioactivity useful?

Automatic thickness monitoring of paper, metals etc in a factory.

Radioactive tracers – for medical use.

Carbon Dating

Uranium Dating

Smoke Alarms

How does a Star Form?

9 marks


How does a Star Form?• Star are formed from clouds of dust and gas.• Gravity pulls the clouds so they come spiralling inwards. • The gravitational energy is converted into thermal (heat) energy and

therefore the temperature rises. • As the temperature rises, hydrogen nuclei undergo nuclear fusion. • They form helium nuclei.• They now give out massive amounts of heat and light – they a now a

new star. • Heat continues to be created by nuclear fusion. • This provides an outward pressure which balances the pull of gravity.• This is the stable period – known as main sequence star.

What is a red giant, white dwarf and black dwarf?

4 marks


What is a red giant, white dwarf and black dwarf?

• The star will swell up into a red giant • One way to remember it is like a spot – getting bigger. • A small star (our Sun) will then cool and contract into a white dwarf. • As the light then fades it will become a black dwarf.

How does a Supernova occur?

3 marks


How does a Supernova occur?

• Big stars, however, start to glow brightly again and they undergo more nuclear fusion.

• They expand and contract several times forming heavier elements in various nuclear reactions.

• Eventually they explode in a supernova.

How does a Supernova lead to a black hole?

3 marks


How does a Supernova lead to a black hole?

• The exploding supernova throws out layers of dust and gas.• Leaves a very dense neutron star.• If the star is big enough – it is a black hole.

Where can you find gravity stronger than on Earth?

3 marks


Where can you find gravity stronger than on Earth?

• The matter from a neutron star and white dwarfs and black holes are made is millions of times denser than any matter on Earth because the gravity is so strong it even crushes the atoms.

What evidence is there that we were created from old stars?

3 marks


What evidence is there that we were created from old stars?

• The dust and gas thrown off will form into second generation stars like our Sun.

• The heavier elements in our Sun and the inner planets gives our evidence that we were created from an old stars dying sneeze.

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How is speed calculated and what are the standard units? 3 marks Stimulating Challenging Innovative Exciting Nurturing Creative Engaging John O’Gaunt Science