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www.GOALias.blogspot.comthe paper ball in by blowing into thebottle.Paheli and Boojho are thinking aboutthe following question:Why is it difficult to force the paperball into the bottle?Activity 8.3Blow the balloonsTake two balloons of approximatelyequal size. Put a little water into thePaheli thinks that the strip will belifted up. Boojho thinks that the stripwill bend down.82Fig. 8.4 Blowing between the balloonsballoons. Blow up both the balloons andtie each one to a string. Hang theballoons 8–10 cm apart on a cycle spokeor a stick. Blow in the space betweenthe balloons.What did you expect? Whathappens?Try different ways of blowing on theballoons to see what happens.Activity 8.4Can you blow and lift?Hold a strip of paper, 20 cm long and3 cm wide, between your thumb andforefinger as shown in the Fig. 8.5. Nowblow over the paper.Fig. 8.5 Blowing over a strip of paperWhat do you think will happen tothe paper?Let us try to understand theobservations in Activities 8.2, 8.3 and 8.4.Were the observations along the linesyou thought? Do you get the feelingthat the increased wind speed isaccompanied by a reduced air pressure?When we blow into the mouth of thebottle, the air near the mouth has higherspeed. This decreases the pressurethere. The air pressure inside the bottleis higher than near the mouth. The airinside the bottle pushes the ball out.In Activity 8.3 you saw that when youblew between the balloons, they movedSCIENCE