This post contains all the important formulas that you need for A Level Physics. (Equivalent to AP Physics) If you do not recognise any of the terms listed here, you should go review the respective topic.

Please drop me a comment if I missed out any particular important definitions.

**Measurement:****Random errors** are errors of measurements in which the measured quantities differ from the mean value with different magnitudes and directions.

**Systematic errors** are errors of measurements in which the measured quantities are displaced from the true value by fixed magnitude and in the same direction.

**Accuracy** is a measure of how close the results of an experiment agree with the true value.

**Precision** is a measure of how close the results of an experiment agree with each other.

**Thermal Physics:**

The** internal energy** is a function of state and the total microscopic kinetic and potential energies of the particles composing the system.

The **specific latent heat of fusion**, L_{f} , is defined as the amount of heat required per unit mass to change a substance from the solid phase to the liquid phase without any change in temperature

The **specific latent heat of vaporization**, L_{v}, is defined as the amount of heat required per unit mass to change a substance from the liquid phase to the vapor phase without any change in temperature.

**First law of thermodynamics** state that internal energy is a function of state and the increase in internal energy is equal to the sum of the heat supplied to system and work done on system.

**Kinematics:****Speed** is the rate of change of distance traveled with respect to time.

**Velocity **is the rate of change of its displacement with respect to time.

**Acceleration** of an object is the rate of change of its velocity with respect to time.**Forces And Dynamics:****Normal contact force** is a force perpendicular to the surface experienced by a body when it is in physical contact with something else.

**Hooke’s Law** states that within the limit of proportionality, the extension produced in a material is directly proportional to the load applied.

The **principle of moments** states that, when an object is in equilibrium, the sum of anticlockwise moments about any point equals the sum of clockwise moments about the same point.

The **moment of a force** is the product of the force and the perpendicular distance between the axis of rotation and the line of action of the force.

A **couple** is a pair of forces, equal in magnitude but opposite in direction, whose lines of motion do not coincide.

**Centre of gravity** is the point on an object through which the entire weight of the object may be considered to act.

**Stability** of an object refers to its ability to return to its original position after it has been displaced from that position.

**Pressure** is force acting per unit area.

**Upthrust/buoyancy force** is an upward force on a body produced by the surrounding fluid (i.e., a liquid or a gas) in which it is fully or partially immersed, due to the pressure difference of the fluid between the top and bottom of the object.

**Archimedes’ Principle** states that the upthrust experienced by an object partially or entirely immersed in a fluid is equal to the weight of the fluid displaced by the object.

**Newton’s first law of motion** states that a body will continue in its state of rest or uniform motion in a straight line unless an external resultant force acts on it.

**Newton’s second law** states that the rate of change of momentum of a body is proportional to the resultant force acting on it and the change takes place in the direction of the force.

**Newton’s third law** states that: If body A exerts a force on body B, then body B exerts a force of equal magnitude but in the opposite direction on body A.

The **principle of conservation of momentum** states that the total momentum of a system of objects remains constant provided no resultant external force acts on the system.

**Work, Energy And Power:****Work** is the mechanical transfer of energy to a system or from a system by an external force on it.

**Heat** is the non-mechanical transfer of energy from the environment to the system or from the system to the environment because of a temperature difference between the two.

The **principle of conservation of energy** states that energy cannot be created nor destroyed in any process.

**Gravitational Potential Energy** is defined as the amount of work done in order to raise the body to the height h from a reference level.

**Power** is defined as the rate of work done or energy converted with respect to time.**Circular Motion:****Angular displacement**, θ is the angle subtended at centre of a circle by an arc of equal length to the radius.

**Angular velocity**, ω is the rate of change of angular displacement with respect to time.

The **period** T of an object in circular motion is the time taken for the object to make one complete revolution.

The **frequency** f of an object in circular motion is the number of complete revolutions made by the object per unit time.**Waves:****Displacement** is the distance moved by the particle from its equilibrium position.

The **amplitude** of a wave is the maximum displacement of the particle from its equilibrium position.

The **wavelength** is the distance between 2 successive points on a wave which are in phase with one another.

The **period** is the time taken for a particle on the wave to complete one oscillation.

The **frequency** of a wave is the number of complete oscillations that pass through a given point in 1 second. (Units: Hertz(Hz) or s^{-1})

A **compression** is a region where particles are close to one another. (High pressure)

A **rarefaction** is a region where the particles are further apart. (Low pressure)

**Phase Difference** (φ) between two particles or two waves tells us how much a particle (or wave) is in front or behind another particle (or wave).

**Intensity** of a wave is the rate of transfer of energy per unit area perpendicular to the direction of travel of the wave.**Oscillations:****Periodic motion** is the regular, repetitive motion of a body which continually retraces its path at regular intervals.

**Period** T of a periodic motion is the time to make one complete cycle.

**Frequency** f of a periodic motion is the number of cycles per unit time.

**Angular frequency** of a periodic motion is the rate of change of angular displacement with respect to time.

**Displacement** of an object is the distance of the oscillating particle from its equilibrium position at any instant.

**Amplitude** of a periodic motion is the magnitude of the maximum displacement of the oscillating particle from the equilibrium position.

**Simple Harmonic Motion** (SHM) is defined as the oscillatory motion of a particle whose acceleration a is always directed towards a fixed point and is directly proportional to its displacement x from that fixed point but in the opposite direction to the displacement.

**Damping** is the process whereby energy is taken from the oscillating system.

**Natural frequency** of the system is the frequency at which it will vibrate freely.

The definitions for waves aren’t correct since a lot of them assume that the waves require a medium. The definitions as a whole are correct but a lot wouldn’t get you the marks in an exam.

powerful definitions ..like them

I learn alot from you guys

what of charge density?

EL PENE