Click to edit project
Click to edit project description
Page 1 of 2 A clean break Sometimes, what looks like an accident turns out not to be. It may be vandalism, insurance fraud or even murder. Accident investigators need to establish whether an incident happened accidentally, or was caused deliberately. For instance, did something break through wear and tear, or was it tampered with? In this project, you will study various materials that have been broken in various ways. Your objective is to find ways of distinguishing between the various causes by studying the broken pieces. Getting Started How many ways of breaking (not cutting) solid materials can you think of? Devise and carry out experiments to see which types of materials break under various conditions. Gradually increasing tension: Hold strips of the material in a clamp and hang a mass so it pulls down on the material. Gradually add more masses until it stretches or breaks. It might be wise to design these experiments yourself but ask a trained adult to help you carry them out. If something needs a really large mass to break it, then just make a note of the fact – don’t keep increasing the mass until it does break! Examine and compare the broken edges. Working at the cutting edge of science: Try cutting and sawing the same materials. Examine the cut/sawn edges carefully, looking for telltale marks or patterns that indicate the separation method. Compare cut and sawn samples, and also compare them with the samples above. Investigate whether the type of blade or saw affects the results. Getting to know the ropes: Ropes are designed to be very flexible, so impact or bending won’t break them. They are also designed to withstand tension, so snapping would need more force than you could safely apply. Think up a way to scale down the experiment so that you can snap the fibres. A rope might also wear away by rubbing against a hard and/or rough surface. Think up a way of simulating this, to obtain samples that have worn through. Examine the fibres of cut, sawn, snapped and worn ropes. Look for telltale differences. Try both natural and synthetic fibre ropes. To see the effect of weathering, test string (for example, garden twine) that has been left out in the open air over winter. Compare it with new string of the same kind. Click to edit project description Things to think about You could investigate the effect of: Sudden impact, for example, dropping a mass onto the material Gradually increasing the load or the bend angle. Hold the material in a vice and hang a mass on one end, gradually add extra masses so the material bends. Flexing backwards and forwards Sudden tension, for example, if someone is attached to a climbing rope and they fall there will be a sudden tension pulling on the rope. How can a test ‘mimic’ this? Useful Resources Why not see if you can get in touch with real-life accident investigators Investigating a claim: Imagine that you are insurance claim investigators. You have been given two pieces of rope and you need to decide how the end of the rope became separated from the rest. Use the knowledge you gained above to examine the rope end and draw conclusions. Present your findings to the claims assessor with supporting evidence. Explain how the evidence supports your conclusions. .
