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by Procheta Mallik

Introduction

One of the most fun toys, a 2-in-1 pump made from the most basic of materials. A misty spray and a solid sprinkle will always leave you asking for more!

Video Overview

    • Handle the scissor with care

    • Be careful about the pokey end of the skewer

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  1. Cut 2 pieces of straw, each 6-10 cm in length (the two pieces do not have to be equal).
    • Cut 2 pieces of straw, each 6-10 cm in length (the two pieces do not have to be equal).

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    • Cut a piece of foam with straight edges, having approximate dimensions of 2cm x 2cm x 1cm.

    • Optionally, you can use piece of thermocol or rubber

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    • Along one of the longer edges of the foam piece, place one of the cut pieces of straw such that the end of the straw and an edge of the foam piece align exactly. Then use insulation tape to fix it at that position

    • Now take the other piece of straw and place it along the edge perpendicular to the first straw. Make sure about a half of the first straw’s opening is blocked by the second straw and tape the second straw on at this position.

    • The two straws can now be distinguished by the fact that one of them is `half-blocked’ (first piece) and the other is `unblocked’ (second piece)

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    • Take the skewer and with the sharp end poke it into the foam piece such that it bisects the right angle between the straws

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    • Insert the unblocked straw into a cup of water and blow from the straw that is half-blocked. A perfect misty spray should emanate from the gap between the straws.

    Vishal: We need to show the spray coming out.

    Procheta Mallik - Reply

    • Holding the skewer, submerge the foam-end of the straws into a cup or mug filled with water such that the straws are only slightly submerged. Now spin the skewer back and forth with your fingers and water should sprinkle out from both the straws creating a nice circular water-patch on the floor and perhaps sprinkling your shirt too!

    • Use coloured water to make this activity even more fun!

    Vishal: We should remove the sprinkler section. It can be confusing.

    Procheta Mallik - Reply

    • The straws are misaligned

    • One straw is not blocking enough of the other

    • Blowing from the wrong straw

    • Opening of the straw/s have been blocked by tape

    • Not blowing hard enough

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    • Straw openings blocked by tape

    • Skewer not inserted accurately enough, i.e. almost parallel to one of the straws

    • Straws either submerged too much or not at all into water

    • Twirling done too slowly

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    • Blow and suck from each straw while the other is immersed in water. During which scenario does the spray come out? Why? (Observe closely)

    • Measure the length of the unblocked straw

    • Put 2 teaspoons of water (10 ml) in a table spoon and place the unblocked straw in it. Measure the time it takes to empty the spoon of all its water as a spray while you blow as hard as you can through the half-blocked straw

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    • Measure the angles of the 2 straws with respect to the skewer

    • Once again, immerse the straws by 1 cm in the water and measure how far the water is ejected when you twirl the skewer

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    • Make the same toy with longer straws

    • Make the same toy with straws at different angles: acute and obtuse

    • You already have a 2-in-1 toy: mist and sprinkler. Make it a 3-in-1 toy by making one of the straws whistle!

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    • Make the same toy with straws of different stiffness and/or gauge

    • Make the same toy with used pens/sketch pens

    • Mount the mist toy on a small bottle

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    • At which angle (sprinkler) would you get the maximum horizontal distance? What would be the advantage of keeping the angle low? At what angle do you have to throw a ball for it cover the largest horizontal distance?

    • Figure out the direction and trajectory of the ejected drops in the sprinkler

    • Use different liquids (e.g. oil, milk, petrol etc.) to play with the sprinkler and note down your observations

    • Verify Bernoulli’s Principle using the Mist-spray [Note that this is an involved exercise that will require additional research, appropriate for children 15+]

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Finish Line

One other person completed this guide.

Kailash NR

Member since: 05/02/2017

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67 Guides authored

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