3Turn-9
From MrReid.org Wiki
Revision as of 07:59, 21 May 2012 by Ellie (Talk | contribs) (New page: ==Outcomes== * Pupils can sketch the shape of Force verses Extension graphs for helical springs, metal wires and rubber bands. *Pupils can identify and recall that the initial linear regi...)
Contents
Outcomes
- Pupils can sketch the shape of Force verses Extension graphs for helical springs, metal wires and rubber bands.
- Pupils can identify and recall that the initial linear region of a force-extension graph is associated with Hooke's law.
- Pupils associate elastic behavior with the ability of a material to recover its original shape after the forces causing deformation have been removed.
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
Pupils recapping ideas from previous two lessons
- Sketch from memory the force extension graph for a spring and an elastic band
- Identify regions where Hooke’s law applies
- Can you sketch the graph for a wire?
Main Body of Lesson
Hand out wire to pupils GOGGLES NEEDED!
- Pupils wrap the thin wire several times around one of their pencils, then take the other end of the wire and wrap it several times around another pencil leaving at least 5 cm of wire between the two pencils.
- Pupils pull carefully and slowly on the two pencils to try and stretch the wire.
- The wire should be difficult to stretch and then with additional force it should yield a bit and then break.
Demo force extension experiment for a wire using vernier scale
GOGGLES NEEDED!
- Collect class data
- Students to plot graph of extension vs. force for a wire
- Discuss ideas + come to a conclusion
Summary page in classwork books
- Students to look at 3 graph types made over the past 3 lessons
- On 1 A4 page – mini sketch of each one with description as to what each shows
- Use key words – Elastic limit, Hooke’s law, linear, non-linear, directly proportional
Show how energy is area under graph line
- Quick sketch
Plenary
Quiz Quiz Trade