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Minor Versionm

by Kailash NR


Compare the elasticity of cotton thread, metal wire and rubber band by coiling them around a pen/pencil.

Video Overview

    • Be careful with the pokey ends of the binding wire

    • Exercise caution while using cutters/scissors

  1. Take a piece of thin binding wire - about 20cm long.
    • Take a piece of thin binding wire - about 20cm long.

    • Now wrap the wire around the pencil as shown in the figure.

    • Continue this until all of the wire is wound around the pencil, without overlapping.

    • It's okay if the wire is shorter or longer than the mentioned length - as long as it coils around the pencil at least a few times.

    • Once the wire is completely wound around the pencil, let go off any pressure on the wire and observe.

    • Then push the wire together as shown.

    • Start pushing the wire towards the end of the pencil inch by inch.

    • Finally, completely remove it from the pencil and observe its shape.

    • You can remove the coiled wire from either side of the pencil - whichever is closer.

    • Cut a piece of cotton thread about 25cm long.

    • Start coiling the thread around the pencil as shown.

    • Keep coiling until the whole thread is wrapped around the pencil.

    • It's okay if the thread is longer or shorter than the mentioned length as long as it coils at least a few times around the pencil.

    • Once the thread is completely coiled around the pencil, let go of any force on the thread and observe.

    • Then, start pushing the thread together and towards the corner of the pencil.

    • You might have to apply some pressure to push the thread towards the end of the pencil. Try and avoid any overlapping of coils

    • Push the thread off the pencil, as shown, and observe!

    • Take a rubber band of medium size.

    • Cut it open with scissors so that it is no longer a loop.

    • Start coiling the rubber band around the pencil as shown in the figure.

    • Do this until the whole rubber band is coiled - do not stretch the rubber band.

    • Release the pressure you're applying with your finger on the rubber band.

    • And observe!

    • It is better to start coiling the rubber band towards the end as it will be hard to push it towards the end later.

    • This time, stretch the rubber band and wrap it around the pencil. Once the whole rubber band is coiled, release the pressure and observe!

    • After the experiments, this was the state of all the materials. Try it out yourself!

    • If the rubber band breaks while stretching, do not worry - use a new one and apply less pressure on it this time.

    • If it is hard to push the cotton thread towards the end, coil it really tight towards the edge from the beginning itself.

    • If you cannot find a pencil, any cylindrical thin object will do (pen, sketch pen etc).

    • Try this with different materials! You could use silk threads, wires, straws etc.

    • Does the newly shapes wire (coil) act as a spring? Try hanging a weight off it to see if it spring back up.

    • What would happen if you left the cotton thread for a while on the pencil and then removed it? Would you have the same result?

    • What happens to all of these objects every time you release pressure? Do they change much from their original shape?

    • What happens when you remove the support of the pencil if they did maintain their new coiled shape after removing pressure?

    • Would you consider the spring you made out of binding wire elastic? Is the binding wire in itself elastic? What about the rubber band?

    • Does it surprise you that to make a spring (which is elastic), you need metal (which is inelastic)? And that with an elastic material (rubber band) you cannot make a spring?

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