PhysicsBhanu · Class 4-5
Dabaav ka hisaab: zor ÷ jagah, aur gehre paani ka zor
Chalo ek kahani sunte hain. Aman ki dadi sabzi kaatne se pehle chaaku ki dhaar tez karwaati hain. Ek din Aman ne poochha: 'Dadi, dhaar wala chaaku aasaani se kyun kaatta hai?' Dadi muskurayi: 'Dabaav ka khel hai!'
Socho pehle… phir dekho jawab
Dabaav = zor ÷ jagah. Tez dhaar ki jagah bahut patli, isliye haath ka chhota sa zor bhi bahut dabaav banata hai. Aur paani-hawa bhi dabaav dalte hain.
Dabaav = zor ÷ jagah (area). Zor badhao ya jagah ghatao — dabaav badhega. Isliye chaaku ki dhaar patli, keel nukeeli; aur bojh uthane wali patti chaudi, tractor ke tyre chaude.
Paani ka dabaav: paani apne upar ke paani ka bojh uthata hai. Gehrai badhi, phir upar ka bojh badha, isliye neeche dabaav badha. Teen chhed wali bottle mein sabse neeche ki dhaar sabse door jaati hai. Paani deewar par bhi har taraf dabata hai, sirf neeche nahi.
Hawa ka dabaav: hamare upar hawa ki ek moti chaadar hai, jo har cheez par dabaav daalti hai. Straw se juice peete ho toh andar ki hawa kheench lete ho; bahar ki hawa juice ko upar dhakel deti hai.
Humne kya kiya :- Chaaku ki dhaar, bottle ke chhed aur straw ko dabaav ke hisaab se samjha.
Isse kya hua :- Pata chala ki dabaav = zor ÷ jagah, aur paani jitna gehra, dabaav utna zyada.
Ghar pe try karo
Bade ek khaali plastic bottle mein ek seedhi line mein teen chhed (upar, beech, neeche) kar dein aur unpar tape chipka dein. Bottle bharo, aangan mein rakho, tape hatao. Teeno dhaar kitni door giri? Ungliyon se naap kar copy mein likho. Paani paudhon ko do.
Wow!
Har 10 metre gehre samundar mein paani ka dabaav lagbhag ek poore vayumandal (hawa ki poori chaadar) jitna aur badh jaata hai!
Mummy-Papa ke liye
Aaj bachche ke saath teen chhed wali bottle ka prayog kijiye (chhed aap kijiye) aur poochhiye: 'Neeche ki dhaar sabse door kyun gayi?'
3 sawaal
- Dabaav ka sahi hisaab kya hai?
Jawab dekho
Zor ÷ jagah. Dabaav = zor ÷ jagah (area); jagah chhoti toh dabaav zyada.
- Paani se bhari bottle mein sabse door dhaar kaunse chhed se nikalti hai?
Jawab dekho
Sabse neeche wale. Gehrai ke saath upar ke paani ka bojh badhta hai, isliye neeche dabaav sabse zyada.
- Straw se juice upar kaise aata hai?
Jawab dekho
Bahar ki hawa ka dabaav juice ko upar dhakelta hai. Andar ki hawa kheenchne par bahar ki hawa ka dabaav juice ko straw mein upar dhakelta hai.
NCERT se jodo: NCERT Class 4-5 EVS — paani aur hawa ke gun; Class 8 Science ka 'force aur pressure' wala vichar (idea in words)