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• Use the balance to measure the mass of the trolley (with no extra masses added). Start with one 0.1kg mass hanging on the end of the string and no masses on the trolley. Release the trolley from rest and record the time it takes to travel between the light gates (which will be shown on the data logger) as well as the velocity of the trolley at each light gate (also on data logger). Add one 0.1kg mass to the trolley and repeat. 
• Continue adding masses to the trolley until all of the masses are used up (or a reasonable number have been used in order to get comprehensive results), recording the time taken and the velocity at both gates each time. Calculate the acceleration for each recorded value using a = v−u. Plot a graph of acceleration against mass, which should give a smooth curve showing an inverse relationship between the two variables. Plot a graph of acceleration against 1 , which should give a straight line.
• Counteract friction by raising the ramp slightly so that, when pushed, the trolley will roll to the end of the ramp without stopping. You must also measure the length of the card attached to the trolley and input that into the data logger so that it can calculate the velocity of the trolley as it passes through the light gates. The force in the string must be kept constant, so the mass at the end of the string must remain the same. You may need two sets of light gates: one on each stand to measure the velocity of the trolley at each point, and a set of two to measure the time taken to travel between them.
• To observe waves in a liquid, set up the ripple tank and place a piece of paper and a ruler underneath the tank where the light and shadows of the waves are visible. The ruler must be perpendicular to the wavefronts – you can ensure this by using a set square or anything with a 90 degree corner. Make the waves as slow as they can be whilst still being clearly visible by adjusting the settings of the ripple tank. Use the ruler to measure the wavelength of the waves. It may be helpful to take a photo of the waves with the ruler in the picture so that you can take your measurements without the waves moving.
• Use the stopwatch to time 10 seconds and count the number of wavefronts that pass a fixed point in that time (mark the point on the paper to make this easier). Divide this number by 10 to obtain the frequency of the waves. Mark two points beneath the tank that are a set distance apart (e.g. the length of the ruler, 0.3m) and use the stopwatch to determine the time it takes for one wave to travel between the two points. Using the formula v = f λ , you can calculate the value for the speed of the wave obtained through the wavelength and frequency of the wave. 
• Using the formula v = dt , you can calculate another value for the speed of the wave obtained through the time it took to travel the distance you marked on the paper. Compare these two values for v – if they are close together, it would suggest that the suitability of the equipment is good (remember to refer back to the main aim of the investigation when coming to a conclusion).
• To observe waves in a solid, measure the length of each rod using the ruler. The wavelength of the wave at peak frequency will be twice this length, ensure this is measured in metres. Suspend the rod from the clamp stands using the elastic bands as shown in the diagram. Strike the rod at one end and use the frequency recorder to measure the peak frequency.

  Record this value. Repeat this, striking the rod up to five times and taking an average of the frequency values. Repeat the process with different types of metal rods. Using the formula v = f λ , calculate the velocity of the waves in each rod using the mean peak frequency and the wavelength (2 x the length of the rod). Compare these values with researched values for each type of metal – if they are close, the equipment is suitable.
• Set up the equipment in a darkened room. Place the glass block on the paper and draw around it to ensure that the block will always be in the same place even if you remove it and replace it. Using the protractor, draw a line that is 90o to the surface of the glass block (this is the ‘normal’​). It may be easier to move the block and work from the outline on the paper for this part since you need to continue the line into the glass block outline. Draw three lines as guides for the angles of incidence you will produce (you will shine light along these lines into the block). These will hit the block at the point where you drew the normal. Example angles are 20, 40 and 60. Direct the light along each of these lines in turn and, for each one, make markings where the light leaves the block on the other side. This can be done by drawing dots or Xs and joining them together with a ruler once you have moved the block out of the way
• Connect the point of incidence to the point where the light leaves the block for each angle, which should leave you with something like the diagram above. Ensure that there is a normal line (90 degrees to the surface of the glass as before) at each point where the light leaves the block. Use the protractor to measure all the angles of ​incidence​ ​and ​refraction ​and mark these on the paper. The angle of incidence where the light initially hits the block should be equal to (or very close to) the angle where the light is leaving the block. Always measure angles relative to the normal. 
• Compare the angles of incidence and the angles of refraction for glass into air and air into glass for each angle. For air into glass, the angle of refraction ​should always be smaller ​than the angle of incidence as light slows down when entering a more dense medium. For glass into air, the angle of refraction​ should always be greater​ than the angle of incidence as light speeds up when entering a less dense medium. Plot these results on a graph of angle of refraction against angle of incidence with one line showing glass into air and another showing air into glass.
• Boil the kettle and pour water into each of the beakers, ensuring that they all have the same volume​, and cover each beaker with a lid. You can ensure the volume is the same by using a measuring cylinder or markings on the side of the beakers (provided all the beakers are exactly the same). The lid is important to minimise heat loss through the top of the beaker. Record the initial temperature of each beaker and start the stopwatch. You may need to leave some time before starting to ensure the thermometers are all acclimatised and reading the temperature correctly. Record the temperature of each beaker at regular time intervals (eg. example, every two minutes for a total of 20 minutes or until the water has reached room temperature). It may be helpful to take a picture of all the beakers and read the temperature off of that so that you can take all readings from the same precise time.
• Plot a graph of temperature against time, drawing a different line for each beaker, making sure each is clearly labelled. The gradient will show the rate of cooling for each of the beakers. The results of the experiment should show that the ​matte black beaker cools the fastest​ and the silver beaker cools the slowest​. A digital thermometer will make the results more accurate as it has a much smaller resolution than a normal thermometer.
• In a nuclear reactor, a slow-moving  neutron is absorbed into a nucleus (typically uranium-235). This causes the nucleus to become uranium-236, which is unstable. The entire nucleus splits into two large fragments called ‘daughter nuclei’ alongside two or three neutrons which also explode out of the fission reaction and these can collide with other uranium nuclei to cause further fission reactions. This is known as a chain reaction. The fast moving neutrons carry most of the energy from the reaction with them but before the neutrons can collide with fresh uranium nuclei, they need to be slowed down. Their energy is passed on to other components in the nuclear reactor, which is used to heat water to drive the turbines that turn the generators.
• Nuclear fuel - the uranium or plutonium isotope that will split when triggered by an incoming neutron. The fuel is held in rods so that the neutrons released will fly out and cause nuclear fission in other rods. Moderator, a graphite core, for example, slows the neutrons down so that they are more likely to be absorbed into a nearby fuel rod. Control rods - these are raised and lowered to stop neutrons from travelling between fuel rods and therefore change the speed of the chain reaction. Coolant is heated up by the energy released from the fission reactions and is used to boil water to drive turbines in the power station. Concrete shield - the daughter products of the fission reaction are radioactive and can be a hazard.
• Nuclear fusion is when two small, light nuclei join together to make one heavier nucleus. Fusion reactions occur in stars where, for example, two hydrogen nuclei fuse together under high temperatures and pressure to form a nucleus of a helium isotope.
• The Solar System was formed around 4.6 billion years ago from a large cloud of dust and gas, called a nebula. This collapsed under its own gravity, transferring gravitational potential energy to kinetic energy in its particles. As the nebula collapsed it became denser, and rotated more rapidly. Collisions between particles caused kinetic energy to be transferred as internal energy and thermal energy. The core of the nebula began to form a hot, dense protostar.
• All stars begin life in the same way. A cloud of dust and gas, also known as a nebula, becomes a protostar, which goes on to become a main sequence star. Following this, stars develop in different ways depending on their size. Stars that are far greater in mass than the Sun follow the right hand path: red super giant star → supernova → neutron star, or a black hole (depending on size). Stars that are about the same mass as the Sun follow the left hand path: red giant star → white dwarf star → black dwarf star.
• A star forms from massive clouds of dust and gas in space, a nebula, which are mostly composed of hydrogen. Gravity pulls the dust and gas together. As the mass falls together it gets hot. A star is formed when it is hot enough for the hydrogen nuclei to fuse together to make helium, which releases energy, keeping the core of the star hot. During this stable phase in the life of a star, the force of gravity balanced by higher pressure from high temperatures. When all the hydrogen are used up in the fusion process, larger nuclei form and the star expands to become a red giant. When all the nuclear reactions are over, a small star like the Sun begins to contract under the pull of gravity, becoming a white dwarf. A larger star with more mass will go on making nuclear reactions, getting hotter and expanding until it explodes as a supernova, throwing hot gas into space. This could become a neutron star or a black hole.
• If the nucleus has too many neutrons, a neutron will turn into a proton and emit a fast-moving electron called a beta minus (β-) particle - this process is beta radiation. A beta particle has a mass number of zero. As the beta particle is an electron, it can be written as 0-1e or 0-1β. The beta particle is an electron but it has come from the nucleus, not the outside of the atom. Electrons are not normally expected to be found in the nucleus but neutrons can split into a positive proton (same mass but positive charge) and an electron (which has a negative charge to balance the positive charge) which is then ejected at high speed and carries away a lot of energy. Beta decay causes the atomic number of the nucleus to increase by one and the mass number remains the same.
• If the nucleus has too few neutrons, a proton will turn into a neutron and emit a fast-moving positron called a beta plus (β+) particle - this process is positron emission. A positron is the antimatter version of an electron. It has the same relative mass of zero, so its mass number is zero, but a +1 relative charge. It can be written as 0+1e or 0+1β. Beta plus decay or positron emission causes the atomic number of the nucleus to decrease by one and the mass number remains the same.
• A re-arrangement of the particles in a nucleus can move the nucleus to a lower energy state. The difference in energy is emitted as a very high frequency electromagnetic wave called a gamma ray. After emitting an alpha or beta particle, the nucleus will often still have excess energy and will again lose energy. A nuclear re-arrangement will emit the excess energy as a gamma ray.
• Occasionally it is possible for a neutron to be emitted by radioactive decay, this can occur naturally, ie absorption of cosmic rays high up in the atmosphere can result in neutron emission, although this is rare at the Earth's surface. Or it can occur artificially, eg the work done by James Chadwick firing alpha particles at beryllium resulted in neutrons being emitted from that. A further example of neutron emission is in nuclear fission reactions, where neutrons are released from the parent nucleus as it splits. Neutron emission causes the mass number of the nucleus to decrease by one and the atomic number remains the same.
• If the nucleus is unstably large, it will emit a 'package' of two protons and two neutrons called an alpha particle. An alpha particle is also a helium-4 nucleus, so it is written as 42He. It is also sometimes written as 42α. Alpha decay causes the mass number of the nucleus to decrease by four and the atomic number of the nucleus to decrease by two.