# 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 (k*b*), the universal gas constant (*R*) and Avogadro’s number (N*A*) 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 (ε*r*) in terms of the permittivity of the medium (ε) and vacuum (ε*o*) 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:

- Download your copy of the IB Physics Data Booklet
- Download your free copy of our IB Physics Study Guide

Hope this helps!