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by Procheta Mallik


Where is the pressure of water higher: on the ground floor or the top storey of a building? Here we create a scenario with two bottles and some straw pieces replicating that scene!

    • Handle the scissors/cutter with care

  1. Use 2 identical bottles, preferably small ones, about 200-300ml in volume
    • Use 2 identical bottles, preferably small ones, about 200-300ml in volume

    • Take long straw as 15cms and other 3 small straws of 3cms

    • Using scissors, make 2 holes on each of the caps so that the stiff straws fit in snugly

    • Both caps will have 2 holes on each, almost like eyes!

    • Fix two of the small straws in one of the bottle caps, as shown in the picture, such that they protrude at different heights from the top

    • Fix the full straw and the other small piece on the other bottle cap.

    • Make sure that in both bottle caps, the level of the protrusion of the shorter straws is the same on the outside.

    • Fill the bottles with water (preferably coloured to make it more fun and visible!) till the brim and screw the caps on tightly

    • Invert the full bottles simultaneously over a receptacle, or sink, or outdoors

    • What happens next??

    • Do the bottles empty at all? At the same rate?

    • If not at the same rate, which one empties first? Why?

    • Why are two straws put in each bottle cap?

    • Try emptying the bottle using only one straw!

    • The bottles are not of identical volume

    • Holes on the bottle caps should be tight enough to hold the straws; if they aren't, you can glue the gaps

    • The bottles were not inverted simultaneously

    • The straws get squeezed in the bottle cap holes, thereby preventing an outflow altogether

    • Small straws of equal length

    • Straws not aligned properly inside the bottle cap

Finish Line

Suchitha Vishwa

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