# Why do Fish Swim and Birds Fly?

In this project work, we would like you to study some type of motion. You will need to make several decisions before you start. The suggestions given here are only meant to get you thinking - you do not need to follow any of these if there are other aspects of motion that you would prefer to investigate. However, you will need to think about each of these questions before doing anything else.

1. How will you collect your data?
2. Which people or animals will you study and how will they be moving?
• Do you want to study walking, running, swimming, flying, ... ?
• Do you want to study people or animals?
• Do you want to make a comparison - for instance, do boys and girls run in the same way? Do dogs and cats walk in the same way? How does the way you move differ in breast-stroke and butterfly stroke? ...
3. What aspect of motion do you want to investigate? The answer to this question will decide how you go about interpreting your data, and should be decided BEFORE you start to collect data, to ensure that the data you collect is appropriate.
• Do you want to know exactly how people or animals move?
• Do you want to look at the effect of speed?
• Do you want to find out how to move more efficiently?

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## Collecting data

The best way to get good data to study motion is to video it, then you can use each frame to investigate what is happening. If you do not have a video camera available, you can use photos, using a stop watch so you know the time interval between each shot. If you do this, you may find it helpful to have more than one camera and stop watch available, so that you can get as good a coverage of the person or animal moving as possible.

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The image below shows successive positions of a butterfish at
intervals of 0.05 seconds. Each square has side length 1 inch.
The crosses mark the wave that passes along the fish as it moves.

How you choose to analyse and interpret your data is up to you. Here are some suggestions you might consider:

• How does speed affect motion? Use the frame rate of your video footage or the intervals between photos to calculate the speed of motion.

- Does it remain constant or does it vary?
- Does the person / animal move in the same way at different speeds or not?
- How do they accelerate / decelerate?

• How efficient is the motion? There are many different ways to think about efficiency, and you could research what top trainers look for. Questions you might use:

- How does speed relate to size? Are longer / heavier people or animals slower or faster than shorter / lighter ones?
- Do faster animals / people move in a different way from slower ones?
- You could find data on top athletes or the fastest birds / animals to use for comparisons.

## Websites

### Acknowledgements for use of photos in Kiran's presentation:

Please use only photos which you have permission to use in your own presentation.

1. Nicole Bouglouan: photos of birds on http://www.pbase.com/
2. R.W. Scott: high speed photos of birds on http://www.gregscott.com/rwscott/rwscott.htm
3. Tim Nicholson: pics of swimming fish on http://www.scubatravel.co.uk (and Jill at Scubatravel, for her valuable help)
4. Bird Flight, Georg Ruppell (van Nostrand Reinhold Company)
5. http://www.infovisual.info