Brittle – Will break or rupture suddenly
Plastic – Can be distorted but does not return to its original shape
Elastic – Can be distorted but returns to original shape
Stress – When forces are placed on an object
Strain - The way stress is reacted to.
Plan
- I am going to design an experiment to look at the way different materials react to stress. Some of the materials chosen are brittle and some re plastic. The brittle material will simulate the rock needed to produce earthquakes.
- I will use the following materials:
Wooden Cane
Chew stick
Bread sticks
Chew bar
- I plan to add weights to the above objects and record how they bend or deform up to breaking point. The following apparatus will be used:
2 retort stands
Bosses and clamps
1 meter ruler
1 set of 100g masses with hanger
- The apparatus was set up as shown in the diagram below.
Diagram
Fair test
To ensure a fair test is carried out each object will be clamped with the same length extending from the clamp (20cm). The masses will attach at the same point on each object. The same person will read the measurements each time.
Safety
Take care with weights. The standard lab rules were also followed.
Carrying out the Experiment
The object will be clamped in the retort stand and its height will be noted on the meter ruler. The masses will then be added one at a time and the movement of each object will be recorded. Masses will be added to the object until it breaks. The results will be set out in a table.
Hypothesis
I predict that the bread stick will snap suddenly similar to the rocks in which earthquakes occur.
Results This graph shows the reaction of weights placed on certain materials.
This Table shows all the results our group got from this experiment. All these results are correct as we used the same person to measure the size.
Analysis
I found out in this experiment that the more stress placed on something, the more amount of strain, and the material can only hold so much stress. I found this out because the reaction was more extreme on each object when more weights were added. In the earth, the stress is large enough to snap the rock, which will then produce earthquakes.
Evaluation
I think the experiment went well. My prediction was correct, but I could have predicted more things for this experiment. The Bread stick and the garden cane did not break or snap because the weights were not heavy enough. They may a snapped of broken with a larger weight. To improve my experiment I could test more materials and record what that showed. I could do each result more than once giving me an average and I could use more precise weights and measuring equipment.
Limitations
Only use 100g weights could be used, if we could have used more weights e.g. 10g, 20g etc, I could have got a more precise results table. If we could have had more time we could have tested more materials. We could have got more precise readings if we could use different measuring equipment e.g. Micrometer, Verneer calliper etc.