Docs notes

• Physical quantities are quantities that must be measured, have a magnitude (quantity) and units.
• In physics, it is a must to write to 3 significant figures and use SI units only.
• When measuring, use appropriate units and check whether the unit in question is expressed as the SI unit before converting.
• In a table, separate units by quantity using a forward slash.
• In physics graphs, do not start from zero (false-origin axis) and never write fractions in answers.
• Basic physical quantities in physics include mass, time, temperature, current, and length.
• A homogeneous (balanced) equation in physics is where all the terms have the same unit, are separated by either an addition, subtraction or equals sign, and units are not affected by coefficients or numerical values.
• Errors in measurements come about due to instrument faults and uncertainty is a level of unsureness.
• An error in measurement due to an analogue device is usually half the smallest scale division for every measurement you make.
• Error margins are the admissible range of measurements and it is advisable not to use a measuring device that has a measurement error greater than the object you are measuring.
• When measuring length, you may have an error margin at the start and end.
• In a micrometre screw gauge, measure the larger scale and note answer in mm, record the value where the line meets the revolving structure, add the larger scale to the revolving structure.
• Uncertainties are represented with ± (plus and minus) and when the absolute uncertainty is expressed as a percentage, it becomes a percentage uncertainty (no units).
• The value for the quantity should be stated to the same number of decimal places as the uncertainty and when numbers are added or subtracted, always ADD the uncertainties (NEVER SUBTRACT UNCERTAINTIES).
• The antiparticle may be represented by the corresponding symbol for the particle with the opposite sign for the charge or with a bar above it.
• The strong force acts on protons and neutrons but not on electrons.
• Strangeness refers to how quarks interact with one another.
• Gluons are a type of force carrier in the strong force.
• Leptons are fundamental particles and are not influenced by the strong force.
• Each matter and its antimatter particle have the same mass but opposite charge.
• Mesons include kaons and muons, which are formed of an antiquark and a quark.
• In the quark model of hadrons, the hadrons are made up of fundamental particles called quarks.
• The total number of types of quark or 'flavours' is considered to be six in the quark model.
• The numerous types of subatomic particles are placed into two main categories depending on their properties: hadrons, which are influenced by the strong force, and leptons, which are not.
• The quark flavours have charge and strangeness.
• The strong force is an attractive force that must keep the protons together in the nucleus.
• The strong force acts between nucleons and does not seem to have any effect outside the nucleus, making it a very short range force.
• Hadrons include protons and neutrons, which are formed of quarks (preons).
• When a neutron decays, a down quark changes to an up quark.
• Protons have charge uud, while neutrons have charge udd, resulting in a total charge of 0.
• All fundamental particles have a corresponding antimatter particle.
• Total energy after a collision remains the same.
• The principle of moments states that, for an object to be in rotational equilibrium, the sum of the clockwise moments about any point must equal the sum of the anticlockwise moments about that same point.
• The object reaches terminal velocity when the upthrust and the viscous force equals its weight.
• The upthrust force depends on the density of the fluid.
• The acceleration is initially equal to g, but decreases to zero at the time when the terminal velocity is achieved.
• Impulse is the change in momentum, calculated as force x time, with units of Ns.
• A couple consists of two forces, equal in magnitude but opposite in direction whose lines of action do not coincide (parallel), and the product between the force and the perpendicular distance is referred to as torque.
• For a collision to be perfectly elastic, the relative speed of approach equals the relative speed of separation, and the total kinetic energy before the collision equals the total kinetic energy after the collision.
• Momentum is a vector quantity, the product of mass and velocity, with units of kg ms-1 or newton second (Ns).