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Project work 3: elasticated cups

This project investigates what happens when you join plastic cups with elastic and displace the system from its equilibrium position on varying surfaces. You should try the activities in Part A first, then quantify what you see. Suggestions are given in Part B. Try to find your own way to quantify the scale of movement you see, and graph it in some way. Part C gives extension work.

Part A

  • Join up 5 or 6 plastic cups in a line with equal lengths of thin elastic, say about 20 cm natural length to start with. You may find experimenting with elastic bands the best way to start this. Half fill the cups with rice (or weight them down in some other way). Now place the cups on a large piece of squared paper, so you can mark their positions. Pull one cup away from the other in, say, 2 cm amounts. What happens? What moves where? Mark what happens on your piece of paper at each stage. Decide whether events are "small","medium" or "large".
  • What happens if you only have 3 cups, or if you have 20? Investigate this in a systematic way.
  • What hapens if you join the cups in a different way - does it make a difference?
  • What happens if you vary the lengths of the elastic between the cups?

Part B

  • Find a way to quantify the size of events - aim to find your own way to do this
  • To get you started, you could look at the distances moved by the cups, or the total distance moved

Part C

  • Try different textured surfaces. What difference does it make if the surface is smooth, rough, has bands of roughness on a smooth surface? You could vary the distance between rough bands on a smooth surface in a systematic way. How about if it just has rough patches, rather than bands across the surface... ?