ten little fingers - arvind gupta (4 mb pdf)

SAND HOUR GLASS1. You will need two cleaninjection bottles, an old refill,thorn or divider, sand, blade andsome rubber adhesive.2. Apply cycle puncturesolution on the flat sides of thetwo rubber caps and stickthem back to back.3. Make a see throughhole (2mm) through thecentre of the caps byrepeatedly poking themwith a thorn or a divider.4 You should be able tosee a clear hole in the caps5. Cut a 5 mm long piecefrom an old plastic ball penrefill.6. Insert this refill piecein the hole between thetwo rubber caps.7. The ball pen refill boreprovides a smooth and uniformorifice for the flow of sand.Pulse BeatWith a bit of soft clay orplasticine, fix amatchstick on the pulseof your wrist so that youcan see the end of thematch move slightly eachtime your heart pumpsblood.Does your pulse moveevery second, or fasteror slower? How manytimes do you breathe inone minute?How many steps do youwalk in one minute?8. Fill fine and dry sand in oneof the injection bottles.Assemble the two rubber capsand the other empty bottle ontop of it.Simple Pendulum9. On inverting, sandfrom the top bottle willtrickle down into thelower bottle. By fillingin the right quantity ofsand and calibrating itagainst a standardwatch you can make aone minute sand hourglass.Hold a string with a stone tied to the endso that it can swing without touchinganything. Give it a slight push so that itswings gently. Make the string longer andshorter and notice whether the stoneswings quickly or slowly.Take a 1 metre long string and hang it bya nail so that it swings freely. Give it alight push so that it starts swinging gently.You will find that die time the stone takesto go from one side to the other is onesecond when the string is one metreCount sixty swings to understand howlong one minute is.Practice counting swings with your eyesshut while your friend watches theswinging stone. In this way you can learnto count seconds even without a swingingstone.