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1.3

Major VersionM

by Procheta Mallik

Introduction

Using just a couple of straws of different gauge, we create a wonderful propeller, which addresses many concepts in physics

Tools

Parts

Video Overview

    • Exercise caution when using scissors

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  1. Bend the fat straw in half.
    • Bend the fat straw in half.

    • Nip the two corners at the centre-fold

    • This would give you two diamond holes in the middle of the straw.

    • Make sure the holes are big enough that the thin straw can be inserted easily, but not so big that the straw breaks in half.

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    • Press down each end of the fat straw and seal them with tape.

    • Tape over the end of the straw rather than around it, such that the tape doesn't come off

    • The orientation is very important. In other words, when you look through the diamond holes, both taped ends should look flat to you, i.e. press the back and front and tape the ends.

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    • Nip one corner on each taped end of the fat straw such that they are diagonally opposite each other.

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    • Fold one end of the thin straw, about 2-3 mm from the edge.

    • Nip just one corner so that you get a diamond shaped hole close to one end of the straw

    comments by vishal:

    We usually do not make two holes in the blowing straw. The functionality may not get affected majorly except that the energy of air will get distributed. Also, the variation of making single hole in the rotating straw will have different results if we make two holes in blowing straw.

    Procheta Mallik - Reply

    • Insert the thin straw into the diamond holes of the fat one such that the hole in the thin straw lies within the fat straw.

    • Shut the hole-end of the thin straw with your finger and blow through the other end of the thin straw

    • Your straw propeller should now spin!

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    • The fat straw holes are too small, as a result, the thin straw doesn't fit loosely in them

    • The orientation of the taping is incorrect

    • The diametrically opposite holes in the fat straw are too small.

    • The holes in the fat straw are not diametrically opposite.

    • The thin straw hole is too far from one end and thereby not within the fat straw

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    • Vary the length of the fat straw (double, half etc) and observe its effect on the speed.

    • Make two more diagonally opposite holes in the fat straw. Does it rotate?

    • Cut the blowing end of the blowing straw in a ‘V’ shape, so as to make a sound while rotating the propeller. Refer to Sound - Oboe

    • Make a single corner hole on the rotating (fat) straw

    • Try making the same toy with straws of the same diameter (gauge).

    • Make two holes, instead of one, on the blowing (thin) straw

    • Make the toy hands free, i.e. you shouldn't need to block the open end of the blowing straw with your finger.

    • Make a multi-rotor, by making multiple holes along the blowing straw at spaced intervals and use thumb pins/foam/beads as spacers to create a variant with multiple spinning rotating straws.

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    • Cut the fat straw to different lengths and create propellers

    • Now measure the amount of time each propeller rotates for a single breath

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    • Make two more diagonally opposite holes in the fat straw

    • Does it rotate?

    • If yes, how do the added new holes affect the propeller?

    • Measure and record the time taken for the rotation to stop after a single breath.

    • Measure and record the time of rotation after making one hole

    • Measure and record the time of rotation after making both the new holes

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    • Let's make a sound oboe action reaction propeller

    • Flatten the blowing end of the thin straw and cut it in a triangular shape or inverted 'V' shape

    • Now blow through the `V'-cut end to create a sound as the propeller spins

    • Refer to Sound - Oboe

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    • Make a single corner hole on the rotating (fat) straw

    • Tape the other end

    • Observe if the propeller spins or not

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    • Take two straws of the same diameter

    • Use one straw to make the propeller

    • Use the other straw to make the blower

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    • Make two holes, instead of one, on the blowing (thin) straw, by nipping both the corners after folding appropriately

    • Observe how long the propeller spins after a single breath, using this blower

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    • Make the toy hands free

    • Cut two small pieces of foam (you may use other material, if you so prefer)

    • Using scissors, carve holes in the foam pieces. Make sure the holes are large enough for the straw to pass through

    • Pierce one piece of foam into the blowing straw, now place the propeller and pierce the other piece of foam

    • Tape/seal the end of the straw in such a way that no air escapes from that end

    • Now play with your hands-free propeller

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    • Make a multi-rotor

    • Cut six small pieces of rubber or foam (you may use other material for the separators, if you so prefer)

    • Carve holes into the rubber or foam using scissors

    • Make sure the holes are big enough to pierce them with the straw

    • Make multiple holes in the blowing straw

    • Fit the rubber or foam pieces into the blowing straw along with the propeller; make sure the propellers have enough space to rotate freely

    • Tape/seal the end of the straw in such a way that no air escapes

    • Play with you multi-rotor

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Suhail Ahanger

Member since: 05/02/2017

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