IB Physics IA Ideas: 12 Investigations You Can Complete At Home [UPDATED for 2023]

Independent Variable: Temperature of Water
Dependent Variable: Resonant Frequency of sound produced
Control Variables: Volume of water, density of glass, cross-sectional area of glass rim, humidity/temperature of surrounding air

You should choose which method you plan to make the glass resonate with:

1. Use a slightly wet finger and rub it around the rim
2. Tap the glass with a hard object.

In theory, both methods should produce the same frequency sound, but the second method will produce a sound with a more constant and consistent frequency.

Either way, the physics behind the experiment is the same.

When the wine glass is either struck or a wet finger runs around the rim, the rim begins to freely vibrate. These vibrations cause the rim to form a standing wave pattern. Short video of that here:

You’ll notice that the rim distorts form being circular to a pattern of two ellipses - that vibrate back and forth. This standing wave pattern of the rim causes the surrounding air molecules to vibrate at the same frequency and produces a sound wave within the human range of hearing (20-20000Hz) which means the sound can be heard.

If you add water to the glass, you are increasing the mass of the system and the natural frequency (or the sound produced) will decrease.

Once you have added the water, it is important that you keep the volume of water constant and then change the temperature.

Now, by increasing the temperature of water, you are exciting the water molecules and glass molecules because of the physical contact between the water and the glass. Therefore the molecules within the whole system will have more internal energy and have a greater temperature.

The effects of a greater temperature will be to:

1. Reduce the “stiffness” of the glass and decrease the Young Modulus of the glass. This will have the effect of decreasing the natural frequency of the wineglass.
2. The glass and water will expand in physical size. This will have the effect of increasing the length of the circumference of the rim and thus reduce the natural frequency of the wine glass.

Thus the prediction is that as the water temperature increases the natural frequency of sound produced would decrease. It is difficult to predict an exact mathematical relationship for this, as too many factors will come into play.

Here are some extra resources / videos to help:

1. YouTube Video to explain the standing waves produced: https://www.youtube.com/watch?v=AxWzVPdubjs
2. Background on making the glass ‘sing’ using water, finger and rim: https://recipes.howstuffworks.com/food-facts/question603.htm
3. You can measure the frequency of sound at home using the following app: SpectrumView
4. You can check the sound using this free online tone generator: https://www.szynalski.com/tone-generator/

Idea 2: Fluid Damping

Research Question: How does the cross-sectional area of card attached to a vibrating mass affect the displacement of the mass after twenty oscillations

Independent Variable: Cross-sectional area of damping card
Dependent Variable: Displacement of mass after 20 oscillations
Control Variables: Mass, Initial displacement of oscillating mass, spring constant of spring, (there's more - I'm sure!)

The set up could look like this:

You’ll have to figure out how to recreate this at home.

As you increase the cross-sectional area of the card attached to the oscillating spring, the oscillating system will experience drag due to air resistance. This has the result of increasing the effect of damping on the system.

You could change the area of the card and record the displacement of oscillation after 20 oscillations of the mass (remember to start your oscillations from the same displacement every time). The relationship should be something like:

Where X0 and k are constants

You should be able to produce a straight line graph by taking the natural log of each side.

Idea 3: Paper Helicopter

Research Question: Investigate the factors affecting the terminal velocity of a paper helicopter

Independent Variable: No. of paperclips OR length of helicopter rotor OR width of helicopter rotor
Dependent Variable: Terminal velocity of helicopter
Control Variables: Depends on which independent variable you have chosen

One student in my most recent class made a paper helicopter and investigated factors that affected the terminal velocity of the paper helicopter (e.g. number of paper clips, length of helicopter blade, width of helicopter blade). It was super simple and produced a straight-forward write-up.

NOTES:

• You would drop the helicopter from a height of around 3m. 
• You would only take measurements from a distance of 1m above the ground until it hits the ground.
• You would assume that the helicopter had reached terminal velocity within the first 2m of falling.

You can download the template for the helicopter here.

This free guide will help you get started with your IB Physics IA at home
(and much more!)

Idea 4: Toy Helicopter

Research Question: How does the angle of blade of a toy helicopter affect the lift force on the helicopter?

Independent Variable: Angle of helicopter blades
Dependent Variable: Lift force of helicopter
Control Variables: Number of helicopter blades, width of helicopter blades, rotational speed of blades, weight of helicopter (keep going...)

The helicopter should not leave the scales. The weight of the helicopter will decrease depending on the lift provided by the blades, but it should not leave the scales - use tape to secure the helicopter!

Idea 5: Energy Loss

Research Question: How does the mass of a ball bearing affect the energy loss in a pendulum system when it is released from 90 degrees and collides with a wall?

Independent Variable: Mass of ball bearing (could choose other variable e.g. angle of release)
Dependent Variable: Energy loss (calculated using measurements of height of ball bearing)
Control Variables: Height ball bearing is released, density of ball bearing, density of wall surface....

Release a ball bearing on a string from a 90 degree angle to the wall and measure the energy lost when the ball bearing hits the wall and rebounds off. Measure the height of the rebound and utilise different ball bearing masses. 

Idea 6: Moon Craters (with a difference)

Research Question: How the temperature of grease affects the depth of crater created when a mass is dropped from a known height

Independent Variable: Temperature of grease
Dependent Variable: Depth of crater
Control Variables: mass of ball bearing, height dropped, etc

You may not think that this experiment has much scope for proving your personal engagement BUT there are actually a few areas of measurement in this experiment where you'll have to think very carefully about the precision and accuracy. This will allow you to develop excellent personal engagement with the experiment.

Idea 7: Double Glazing

Research Question: How does the distance between panes of glass in double glazing affect the rate of heat loss?

Independent Variable: Distance between two panes of glass
Dependent Variable: Rate of heat loss
Control Variables: outside temperature, inside temperature, thickness of glass, ambient wind speed, etc.

You should seal the gap between the two panes of glass and try to create an area of low pressure between them. 

The trapped air in the gap is an insulator - it does not stop heat being conducted from the inner pane to the outer pane - but it does slow heat transfer by conduction down a lot!

The air gap is too narrow to allow the air to circulate easily. This therefore reduces the rate of heat transfer by convection. Therefore, an investigation into distance between the gaps would be very interesting.

Idea 8: Siphons

Research Question: How does the cross-sectional area of the pipe in a siphon affect the volumetric flow rate of the water in the siphon?

Independent Variable: Cross-sectional area of pipe
Dependent Variable: Volumetric flow rate
Control Variables: height between columns of water, temperature of water, velocity of water

The challenge with this experiment is how to accurately measure the volumetric flow rate.

Don't get too bogged down in complicated theory. The equation you should be using is really simple:

Volumetric Flow Rate = (Cross-Sectional Area of the Pipe) x Velocity

Please read the information on this webpage

If velocity is constant, then your graph of cross-sectional area on the x-axis and volumetric flow rate on the y-axis should show a graph of direct proportion. The value of gradient should equal the velocity of the water.

This free guide will help you get started with your IB Physics IA at home
(and much more!)

Idea 9: Ramps

Research Question: How does the height of a ramp affect the time taken for a cylinder to roll down the ramp?

Independent Variable: Height of ramp
Dependent Variable: Time taken for cylinder to roll down the ramp

Control Variables: Radius of cylinder, length of ramp

When a cylinder rolls, without slipping, down a slope from rest and rolls down the slope a vertical distance of h, then its gravitational potential energy transfers into kinetic energy. (NOTE: when a cylinder rolls without slipping there is no frictional energy loss.) However, a rolling cylinder can possesses two different types of kinetic energy. Firstly, translational kinetic energy and, secondly, rotational kinetic energy.

There is some basic physics theory to work through (involving the conservation of energy) to find that you plot h on the x-axis and 1/t^2 on the y-axis. The gradient will give you g/3x^2 It should be a straight line through the origin.

Idea 10: Bending Bridge

Research Question: How does the distance between two towers sustaining a flat metallic bar affect the vertical depression/sag produced when a known mass is added?

Independent Variable: Distance between two towers
Dependent Variable: Depression / sag
Control Variables: mass added, position of mass added, Young modulus of metallic bar, breadth of metallic bar, depth of metallic bar, temperature of metallic bar

This website gives a good discussion of the physics and the equation you can use to make your theory / hypothesis. Basically, the sag should be directly proportional to the cube of distance between the towers.

Idea 11: Exoplanets

Research Question: How does the radius of the exoplanet affect the apparent brightest of a star, as the exoplanet transits across the star?

Independent Variable: Radius of sphere that mimics the exoplanet
Dependent Variable: Largest Change in Apparent Brightness from the lamp that mimics the star
Control Variables: Actual brightness of lamp, distance of “exoplanet” from “star, etc

Obviously, you can't do this experiment using actual observed data from home. However, you can model the situation.

You can start with these instructions and develop the experiment/research question to work for you:

Idea 12: Guitars and Violins

Research Question: How does the length of a violin/guitar string affect the sustain time of the violin/guitar string after being plucked with a constant force?

Independent Variable: Length of guitar string
Dependent Variable: Sustain time of string after being plucked
Control Variables: force applied to string, temperature of string, humidity and density of air

Sustain time is the length of time the string vibrates and the sound can be heard. You'd need to use an iPhone app to measure sound volume AND make sure you have a completely silent room. You could try Decibel X PRO: dBA Noise Meter

Hope you've found these 12 ideas useful?

If you'd like more ideas then I have listed 45 IB Physics IA Ideas in this blog post - although you will need more advanced equipment for some of these.

Best Wishes

This free guide will help you get started with your IB Physics IA at home
(and much more!)