Difference between revisions of "3Turn-8"
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*Discuss variables – same as last time - force and extension | *Discuss variables – same as last time - force and extension | ||
*Show how to measure extension using two lines on rubber band | *Show how to measure extension using two lines on rubber band | ||
Revision as of 04:59, 21 May 2012
Contents
Outcomes
- Pupils can sketch the shape of Force verses Extension graphs for helical springs, and rubber bands.
- Pupils can identify and recall that the initial linear region of a force-extension graph is associated with Hooke's law.
Specification References
- 1.27 describe how extension varies with applied force for helical springs, metal wires and rubber bands
- 1.28 recall that the initial linear region of a force-extension graph is associated with Hooke's law
- 1.29 associate elastic behaviour with the ability of a material to recover its original shape after the forces causing deformation have been removed.
Starter
Think back to last lesson - AFL
- What did I learn?
- What did I find easy?
- What did I find difficult?
- What do I want to know now?
Gives students the chance to recall what was done last lesson and assess their learning - What were they able to complete easily? What did they find more tricky?
Main Body of Lesson
Introduce graph shapes
- Linear, non-linear and directly proportional – notes in books
- What was the spring form last class?
- What do they know about Hooke’s Law as found in homework?
- Sketch graph of this – Discuss region where Hooke’s Law applies
- Define Hooke’s Law and state F=kx
Give students one rubber band between 2
- Ask students to stretch them – GENTLY!
- What do you think the graph for this would look like if we did the same experiment?
Experiment to be done as a class
- Discuss variables – same as last time - force and extension
- Show how to measure extension using two lines on rubber band
- Don’t want the band to break – take data as you add masses and then remove them also.
Analysis
- Plot graph
- Conclusion
- What do you notice
- How does the rubber band behave?
- Does it obey Hooke's law?
- What can you say about the graph in relation to the 3 graph types discussed earlier?
