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How to choose the perfect IB Physics Investigation topic in under 15 minutes

ib physics ia ideas ib physics scientific investigation ib physics syllabus 2024 ib physics syllabus 2025+

I'll help you through my simple 4 step process and give you lots of IB Physics IA Ideas


You’ve been browsing IB Physics IA ideas and you’re getting frustrated. I completely understand. Today I’m going to show you the same technique for choosing your physics IA topic that I have taught to thousands of other IB Physics students.

Let’s dive straight into my 4 simple steps to choosing your perfect IB Physics IA topic.


Step 1: Choose a General Area of Interest


Tip: Please don’t overthink this step.

Ask yourself the following questions:

  1. Has any topic sparked my interest in recent physics lessons?
  2. Do I have any notable hobbies or passions?
  3. Have I watched any TV programmes (or YouTube videos) that have sparked my interest?

Let me give you a few examples.

Example 1

I’m 45. I know – I can’t believe it either – I look so youthful!!

I still remember a lesson about geostationary satellites from school. Just because it’s funny… here’s a picture of me at school 20 years ago:

This photo shows 8 teenagers in black blazers. The photo is aged and appears to be taken in 1997. All teenaers in the photo are smiling, with a show of genuine affection for each other

(Can you find me in the picture?)

In class, we calculated the height of a geostationary satellite and discussed the merits of using them for communication. My teacher told me that in 1950 – there were no satellites in orbit. Yet, as science progressed more satellites were being launched into this low orbit to fuel or need for communication and GPS. I became fascinated with the idea of space junk and I still am.

I mean – check this out. This is an artists impression of how the number of satellites in geostationary orbits has increased over the years. Most of this is now non-operational and complete junk!

So in this case, my general topic of interest would be:

geostationary satellites

Example 2

I get around 3-4 emails a day from IB physics student asking for physics IA ideas. One student couldn’t think of ANYTHING that he’d found interesting in ANY of his physics lessons. Boy! That teacher must have been boring!

But he liked football

So in this case, his general topic of interest would be:


Here are some interesting topics of general interest:

  • Bungee Jumping
  • Super Moons
  • Doppler effects
  • Exoplanets
  • Resonance in a wine glass
  • Depth and buoyant force
  • Pendulum damping

and so on…


STEP 2: Choose an Easily Changeable Variable X (Independent Variable)


To get great marks in your physics IA, you need to have a focussed research question. This will be in the following format:

Format: How does Variable X affect Variable Y?

We’ll start with Variable X, which is the independent variable that YOU change as part of your investigation. It needs to be an easily changeable variable about your topic of interest.

If you chose football, then it is easy to change the following things about a football:

  • Pressure of a football
  • Angle of kick of a football
  • Radius of a football

The following variables are easily changeable in Physics. Do any of these relate to your general topic of interest?

Choose one of these for your Variable X:

  • Mass
  • Distance
  • Angle
  • Pressure
  • Radius
  • Volume
  • Temperature
  • Height
  • Power
  • Extension
  • Time
  • Frequency
  • Intensity
  • Cross-sectional area
  • Current
  • Voltage
  • Wavelength
  • Density


Variable X needs to be something that can be measured on a scale (e.g. time, mass, length, pressure, temperature). Don’t choose discrete properties (e.g. type of material, type of fruit, etc)


Step 3: Choose a Easily Measurable Variable Y (Dependent Variable)


Variable Y is the dependent variable that changes AS A RESULT of variable X being changed. Your Variable Y (dependent variable) should be easily measurable.

Let’s stick with the example of football.

Things that can be a easily measured about a football are:

  • Rebound height of a football
  • Range of a football
  • Terminal velocity

The following variables are easily measurable in Physics. Do any of these relate to your general topic of interest?

Choose one of these for your Variable Y:

  • Terminal velocity
  • Range of projectile
  • Rebound height
  • Velocity
  • Temperature
  • Power
  • Initial acceleration
  • Time Period
  • Time
  • Current
  • Resistance
  • Frequency 


It has to be easily measurable! (e.g. frequency, resistance, rebound height, etc). The internal energy of a gas is impossible, the time period of a fly’s wings is impossible too!)


Step 4: Write Down Your Research Question


Format: How does…. (your variable X)… affect … (your variable Y) ?

It is as simple as this!

Write your research question down and check that it makes sense.


Football Examples

  1. How does the pressure of a football affect the rebound height after one bounce
  2. How does the angle that a football is kicked affect the range of the football?
  3. How does the radius of a football affect the terminal velocity of the football?
  4. How does the radius of a football affect the rebound height of a football after one
  5. How does the angle that a football is kicked affect the rebound height?



It would be awful if there were no relationship between your variables... Make sure you can predict roughly what might happen. I know that decreasing the pressure in a football will decrease the rebound height. So I’ve got a pretty good idea that this will work.

The best investigations are able to predict the mathematical relationships between the variables. 


So…. you have your investigation research question, but is it any good?


Extra Tip: Focus ONLY on one Variable X


Your investigation will be great if you choose a well-focussed research question. Don’t include two or three related investigations in one lab report.


Poor Research Questions Have Multiple Independent Variables:

How does the volume and radius affect the resistance of electrical putty?

This research question means that two sets of data will be required. The resulting investigation will lack the depth of analysis needed to earn high marks.


Extra Tip: Focus ONLY on related physics


Consider this research question:

How does temperature affect the coefficient of resistution of a tennis ball?

This investigation would be rubbish if it only includes two pages on the history of tennis. However, if you show an innovative method, explain the relevant background theory, and write an interesting report – you can earn full marks!


Terrible IB Physics IA Ideas


  • Which is the best method to measure time?

The Y variable (time) is measurable. The X variable is not defined. How do you define what the best method is? relative uncertainty? accuracy? This investigation is much too hard.


  • How does the type of surface affect the static friction?

The Y variable is measurable (static friction). The X variable discrete (type of surface). This means that you will have to plot a bar chart, which is rubbish for IB Physics.


How Many Marks is the Perfect Research Question Worth?


The quality of the research question will impact the amount of marks you can be awarded in the Research Design section of the IB Physics IA Rubric.


Here is how to get full marks in the Research Design Section:

  • The research question is described within a specific and appropriate context.
  • Methodological considerations associated with collecting relevant and sufficient
    data to answer the research question are explained.
  • The description of the methodology for collecting or selecting data allows for the
    investigation to be reproduced.

Your research question with context should contain reference to the dependent and independent variables, include a concise description of the system in which the research question is embedded, and include background theory of direct relevance.

Tip: Taking time to format a clear, focussed research question will help you gain full marks 6/6 in Research Design section of your IB Physics Scientific Investigation






I know that finding a good Physics IA topic is difficult, but my 4-Step Plan detailed above will show you how quick and simple it can actually be.

Just remember that your research question needs to be focussed and in the form of:

Format: How does…. (your variable X)… affect … (your variable Y) ?

  • Variable X is the independent variable and should be easily changeable
  • Variable Y is the dependent variable and should be easily measurable.

You need to have a rough idea of what might happen. It would be even better if you knew if they variables were directly proportional, indirectly proportional, etc.

Don’t worry if you’ve chosen the same topic as someone else. If you’re stuck - you can always choose one from this handy list of 100 IB Physics IA ideas.

Finally, I really encourage you to check out my most popular article, The ULTIMATE Guide To A Grade 7 IB Physics Scientific Investigation. In this long article, I'll start with other thoughts on the perfect IB Physics IA idea, but then I delve more deeply into how to collect data and which structure you should use in your Physics IA report.

Hope this helps

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