Introduction
One of the most fun toys, a 2in1 pump made from the most basic of materials. A misty spray and a solid sprinkle will always leave you asking for more!
Video Overview


Cut 2 pieces of straw, each 610 cm in length (the two pieces do not have to be equal).



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



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.



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



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



Holding the skewer, submerge the foamend 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 waterpatch on the floor and perhaps sprinkling your shirt too!



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 halfblocked straw



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



Make the same toy with longer straws

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

You already have a 2in1 toy: mist and sprinkler. Make it a 3in1 toy by making one of the straws whistle!



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



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 Mistspray [Note that this is an involved exercise that will require additional research, appropriate for children 15+]

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