# IB Physics Formulae You Need to Memorise (2025 Syllabus)

## IB Physics Data Booklet: the formulae you MUST memorise to ace your exam!

The formulae below are not in the IB physics data booklet and you should memorise them!

BUT FIRST...

You should also make sure you have a copy of the IB physics data booklet and that you practise using it before your exams.

Now for the important part...

I'll walk through each topic and explain each equation that needs to be memorised.

### Theme A: Space, Time and Motion

#### A.1 Kinematics

Average velocity is defined as the displacement travelled within a certain time. This equation is not in the data booklet:

The horizontal vector component of a projectile:

The vertical vector component of a projectile:

#### A.2 Forces and Motion

At terminal velocity, for an object in free fall:

Newton's 1st Law for a body at rest or in uniform motion:

Newton's 2nd Law for an accelerating mass:

Newton's 3rd Law for action and reaction forces:

Conservation of Momentum (for collisions and explosions):

Variations of the Impulse Equation:

Centripetal Force

#### A.3 Work, Energy and Power

Mechanical energy conservation:

Work-Energy Transferred Theorem:

#### A.4 Rotational Dynamics

Average Angular Velocity:

Moment of Inertia for Solid Cylinder or Disk (about the central axis):

Conservation of Angular Momentum:

Torque and Rotational Equilibrium for an extended body to be in rotational equilibrium, the sum of the torques about any axis must be zero.

Energy Considerations in Rotational Motion: Total Mechanical Energy (if rotational and translational motion are both present)

#### A.5 Galilean and Special Relativity

Relativistic Momentum:

Relativistic Energy:

### Theme B: The Particulate Nature of Matter

#### B.1 Thermal Energy Transfers

Average Speed of Gas Molecules:

#### B.3 Gas Laws

The Stefan-Boltzmann constant (kb), the universal gas constant (R) and Avogadro’s number (NA) are all linked by:

#### B.5 Current and Circuits

Another expression for the formula for internal resistance is:

### Theme C: Wave Behaviour

#### C.1 Simple Harmonic Motion

The defining equation of SHM is:

#### C.2 Wave Model

Intensity of electromagnetic radiation at a distance r from a source with power, P.

### Theme D: Fields

#### D.2 Electric and Magnetic Fields

You can find the relative permittivity (εr) in terms of the permittivity of the medium (ε) and vacuum (εo) is:

The potential difference between two parallel plates, with voltage, V, and separation, d, is:

#### D.4 Induction

Maximum and minimum values for an emf in an ac generator is:

### Theme E: Nuclear and Quantum Physics

#### E.2 Quantum Physics

de Broglie states that particles have wave-like properties and they are linked by the following equation:

Where λ is the wavelength, h is the planck’s constant and p is the momentum of the particle (p=mv)

#### E.3 Radioactive Decay

Example of an alpha decay

Example of a beta decay

If you memorise the formulae listed above NOT listed in the IB physics data booklet you will be well on the way to achieving a 7 in your IB physics exam! You might also want to:

Hope this helps!