4.14 know and use the relationship: kinetic energy = 1/2×m×v^2
Kinetic energy (J) = 0.5 x mass (kg) x velocity (m/s) 2
4.15 understand how conservation of energy produces a link between gravitational potential energy, kinetic energy and work
Because energy is conserved the decrease in GPE = increase in KE, for a falling object if no energy is lost to the surroundings
4.16 describe power as the rate of transfer of energy or the rate of doing work
power is the rate of transfer of energy, or the rate of work done. so p = E/t
5.01 use the following units: degree Celsius (°C), Kelvin (K), joule (J), kilogram (kg), kilogram/metre3 (kg/m3), metre (m), metre2 (m2), metre3 (m3), metre/second (m/s), metre/second2 (m/s2), newton (N) and pascal (Pa)
The units for:
temperature: degree Celsius (°C) or Kelvin (K)
Energy: Joule (J)
mass: Kilogram (kg)
density: kilogram/metre cubed (kg/m3)
distance: metre (m)
area: metre squared (m2)
volume: metre cubed (m3)
velocity: metre per second (m/s)
acceleration: metre per second squared (m/s2)
force: newton (N)
pressure: pascal (Pa)
5.05 know and use the relationship between pressure, force and area:
pressure (Pa) = force (N)/ area (m2)
- Pressure is defined as force per unit area.
- One pascal (Pa) is equivalent to one N/m2
5.06 understand how the pressure at a point in a gas or liquid at rest acts equally in all directions
Pressure in liquids:
Pressure in liquids acts equally in all directions as long as the liquid is not moving.
5.15 explain how molecules in a gas have random motion and that they exert a force and hence a pressure on the walls of a container
Gas laws:
- Gas molecules have rapid and random motion.
- When they hit the walls of the container, they exert a force.
- Pressure = Force/Area
5.16 understand why there is an absolute zero of temperature which is –273 °C
Absolute zero:
- At absolute zero the particles have no thermal energy or kinetic energy, so they cannot exert a force.
- Absolute zero = 0 Kelvin = -2730C
5.17 describe the Kelvin scale of temperature and be able to convert between the Kelvin and Celsius scales
0 K = -273 0C
E.g. 100K = -1730C
2000C = 473K
5.18 understand why an increase in temperature results in an increase in the average speed of gas molecules
As you increase the temperature of a gas, the kinetic energy of the gas particles increases and thus their average speed also increases.
5.19 know that the Kelvin temperature of a gas is proportional to the average kinetic energy of its molecules
The Kelvin temperature of a gas is proportional to the average kinetic energy of its molecules.
5.20 Explain, for a fixed amount of gas, the qualitative relationship between: pressure and volume at constant temperature, pressure and Kelvin temperature at constant volume.
- As you heat the gas, the kinetic energy of the particles increases, and thus so does their average speed.
- This means more collisions per second with the walls, and they exert a larger force on the wall.
- This causes in the total pressure being exerted by the particles to rise.
- If temperature is constant, the average speed of the particles is constant.
- If the same number of particles is placed in a container of smaller volume they will hit the walls of the container more often.
- More collisions per second means that the particles are exerting a larger force on the wall over the same time, so average force exerted on the walls has increased.
6.01 use the following units: ampere (A), volt (V) and watt (W)
The unit for:
Current : amps (A)
Potential Difference : volt (V)
power : watt (W)
6.04 understand the term magnetic field line
Around every magnet there is a region of space where we can detect magnetism (where magnetic materials will be affected).
This is called the magnetic field and in a diagram we represent this with magnetic field lines.
The magnetic field lines should always point from north to south.
6.06 practical: investigate the magnetic field pattern for a permanent bar magnet and between two bar magnets
- Place your bar magnet in the centre of the next page and draw around it.
- Place a compass at one pole of the bar magnet.
- Draw a ‘dot’ to show there the compass is pointing,
- Move the compass so the opposite end of the needle is pointing to the dot,
- Repeat steps 3 and 4 until to reach the other pole of the magnet.
- Do this procedure at least 5 times from different points on the pole of the magnet.
*Tip, try to be as accurate as possible when drawing your dots* - Join up your dots to create the field line plots
6.07 describe how to use two permanent magnets to produce a uniform magnetic field pattern
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A uniform magnetic field is comprised of straight, parallel lines which are evenly spaced. Between two opposite charges on flat magnets, a uniform magnetic field is formed. |
6.08 know that an electric current in a conductor produces a magnetic field around it
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A current travelling along a wire produces a circular magnetic field around the wire. The magnetic field direction can be determined using the right hand grip rule. |
6.12 understand why a force is exerted on a current-carrying wire in a magnetic field, and how this effect is applied in simple d.c. electric motors and loudspeakers
Motor
- Current flows in the wire/coil.
- This creates a magnetic field around the wire/coil.
- This magnetic field interacts with the field from the permanent magnet.
- This produces a force on the wire/coil which moves the wire/coil.
- The split-ring commutator changes the direction of the current every half turn as it spins. This reverses the direction of the forces, allowing the coil to continue spinning.
Loudspeaker
- An alternating current from the source passes though the coils in the speaker.
- This current is constantly changing direction and magnitude
- This current creates a magnetic field around the coil
- This field interacts with the magnetic field from the permanent magnets
- Creating a constantly changing force on the coil.
- This causes the coil to vibrate in and out as the direction of the force changes, moving the cone
- The cone causes vibrations which we hear as sound waves.
6.13 use the left-hand rule to predict the direction of the resulting force when a wire carries a current perpendicular to a magnetic field
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Fleming’s left hand rule. Thumb: force First finger: Magnetic Field Second finger: Current |
6.14 describe how the force on a current-carrying conductor in a magnetic field changes with the magnitude and direction of the field and current
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If you increase the magnitude of the current through a wire or the size of the magnet being used, you increase the force on the wire. If you change the direction of the current or reverse the poles of the magnet, you change the direction of the force on the wire |
7.01 use the following units: becquerel (Bq), centimetre (cm), hour (h), minute (min) and second (s)
the units for:
frequency of decay : becquerel (Bq), 1 (Bq) for 1 decay / sec
distance : centimetres (cm), normally however is (m)
time : hour (h), minute (min) but normally (s)
7.02 describe the structure of an atom in terms of protons, neutrons and electrons and use symbols such as 146C to describe particular nuclei
Atoms are made up of protons, neutrons and electrons.
Protons and neutrons are in the nucleus, electrons are in the shells
7.03 know the terms atomic (proton) number, mass (nucleon) number and isotope
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Atomic (proton) number is the number of protons in the nucleus of an atom. Mass (nucleon) number is the total number of protons and neutrons in the nucleus of an atom. An isotope is an atom of the same element, i.e. it has the same number of protons/same atomic number, but has a different number of neutrons/different mass number. Two atoms with the same atomic number but different mass numbers are isotopes see 7.02 for example |
7.04 know that alpha (α) particles, beta (β−) particles, and gamma (γ) rays are ionising radiations emitted from unstable nuclei in a random process
There are three types of ionising radiation:
Alpha (α), Beta (β) and Gamma (γ)
One radioactive source can release different types of radiation.
Ionisation is when an atom loses or gains an electron, causing it to become an ion (an atom which is positively or negatively charged).
7.06 practical: investigate the penetration powers of different types of radiation using either radioactive sources or simulations
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Detect using a Geiger Müller Tube. Try the three different materials in order, paper then aluminium then lead. Count rate will significantly decrease if radiation is stopped. |
7.10 explain the sources of background (ionising) radiation from Earth and space
- radon in air
- Granit in rocks
- Cosmic rays
- Medical equipment
- Food and drink
7.12 know the definition of the term half-life and understand that it is different for different radioactive isotopes
The Half-life is the time taken for the radioactivity of a specific isotope to fall to half its original value.
7.14 describe uses of radioactivity in industry and medicine
Gamma radiography:
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Medical tracer: – Radioactive tracer put in body (swallowed/injected) – Detector put around body – Computer generates an image |
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Gauging: – Coal absorbs a lot of radiation – If only a small amount of radiation is detected back after it is reflected by what you are trying to gauge, lots of coal is present. |
Radiotherapy
- High doses of radiation are directed at cancer cells
- Cancer cells are killed
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Pipe tracers: – A radioactive material which emits gamma radiation with a short half-life is put in the water – A detector is placed above the pipe – A spike in detected radioactivity suggests a leak in the pipe |
Sterilisation:
- Medical equipment irradiated
- Kills all living matter on tools (e.g. bacteria)
Carbon dating:
7.15 describe the difference between contamination and irradiation
- Contamination:
Occurs when material that contains radioactive atoms is deposited on materials, skin, clothing, or any place where it is not desired.
- Irradiation:
The process by which an object is exposed to radiation.
7.17 know that nuclear reactions, including fission, fusion and radioactive decay, can be a source of energy
- Nuclear Fission:
The process where heavy atoms are split into smaller, lighter atoms. This releases energy.
- Nuclear Fission:
The process where lighter atoms are forced to join together to make heavier atoms. This releases energy.
- Radioactive Decay:
Within the core of the Earth, radioactive isotopes of elements such as uranium, thorium and potassium provide a large proportion of the heat within the Earth through radioactive decay.
7.19 know that the fission of U-235 produces two radioactive daughter nuclei and a small number of neutrons
- A slow moving neutron is absorbed by a uranium 235 nucleus.
- The resulting uranium 236 nucleus is unstable.
- It splits to form two smaller daughter nuclei, three neutrons and gamma radiation.
7.22 understand the role of shielding around a nuclear reactor
Shielding:
- Reactor vessel is made of steel and surrounded by a concrete layer about 5 meters thick.
- This prevents any radiation escaping, even neutrons.
7.25 know that fusion is the energy source for stars
- Nuclear fusion is the source of energy for our sun and all stars.
- In the case of the sun, it is typically hydrogen undergoing fusion to create helium.
8.01 use the following units: kilogram (kg), metre (m), metre/second (m/s), metre/second2 (m/s2), newton (N), second (s), newton/kilogram (N/kg)
units for:
Mass: kilogram (kg)
distance: metre (m)
velocity: metre per second (m/s)
acceleration: metre per second squared (m/s2)
Force: newton (N)
time: second (s)
gravitational field strength: newton/kilogram (N/kg)