case study. case study: investigate mechanical properties of rubber at different temperatures

Case study

CASE STUDY:• Investigate mechanical properties of rubber at

different temperatures

Time frame• Summary of case study and conclusion to be

completed over holiday (or in lesson time once report and results completed and handed in)

• Today: Planning of experiment• Next week: performing experiment and

recording results• Last week: analysis of experiment and

completing investigation. Your Investigation part of case study will be collected in to mark

Case study brief:

• You are to further investigate the disaster of the space shuttle Challenger when after 73 seconds of flight the craft broke apart killing all 7 crew on board.

• The main cause of the break up of the space craft was the failure of one of the craft’s rocket boosters. One of the factors that contributed to this was the under-performance of a rubber ‘o – ring’ component.

• What factors caused the rubber ‘o – ring’ to fail? – relate to the elasticity and structure of rubber.

• What were the implications for NASA after the disaster?

Practical:• Investigate the behaviour of a rubber squash

ball at different temperatures by releasing the ball from a height and measuring bounce height

• Students should choose the appropriate range of measurements, equipment and measuring techniques

• Do your results confirm your findings from your case study?

PLANNING

• What are you investigating?• List equipment, mention why you chose that

equipment and draw diagram.• What are you measuring?• What are the dependent and independent

variables?• How are you measuring and over what range?• How many measurements?

• Is your experiment a fair test?• Have you considered all safety aspects?• How are you presenting data– Table (how many Significant Figures for data?)– Graph

• Uncertainties?• Include units throughout• YOU CAN PERFORM EXPERIMENT IN A GROUP

BUT YOUR PLANNING WRITE UP MUST BE IN YOUR OWN WORDS

• Use your coursework marking grid

From exam board material

• Indicate how you intend to use the data that you collected. For example, you could write: – I will plot stress against strain and use the gradient of the linear

part to find the Young modulus. • Include a diagram showing the arrangement of the

apparatus that you will use. Mark important distances on this diagram and, in particular, mark any distances that you will measure.

• Finally, remember that your plan should show logical thought by describing what you intend to do in sequence. The plan should be written in the future tense but this is not essential.

To consider• Water bath

– Keeps temperature regulated for long periods of time– Only provided temperatures are 30, 40, 50 and 60 degrees

Celsius • Direct heat method

– Hard to maintain temperature– Can select a greater range of temperatures

• Also Ice bath available• Rubber squash ball does require a long time to heat

– Same heating time for each temperature?• Can drop from greater than 1 m height for higher

(proportionally) bounce distance.

IMPLEMENTATION

SUMMARY

• Show them my one note collection – to show clipping and how I have organised my references

• My sources:• see wiki pages for references• how to join:

• assume reader has no knowledge of study• avoid being too technical• NO cut and paste• reference material where content and information was

used• Difference between source and reference?!?!?!?!• try and keep to one page• simple and CONCISE is best• please familiarise yourself with ‘clipping’ programs to

include data or media

From exam board material:

• See google documents stuff as well…..• Students may refer to material on websites but

they should not merely copy large chunks of text into their own work; instead they should use their own words to convey their understanding of what they have read. However, short quotes may be used; the source of any quotes must be clearly identified in the text.

Richard Feynman investigation into shuttle Challenger failure

• http://www.youtube.com/watch?v=UCLgRyKvfp0

Points to remember

• 3 different references• Relate to visit

ANALYSIS

REPORT