PhysicsKhaga · Class 6-8
Pressure: thrust ÷ area, aur paani-hawa ka dabaav
Kabhi socha hai ki ghar ki paani ki tanki chhat par hi kyun rakhte hain, zameen par kyun nahi? Aur neeche ki manzil ke nal mein paani zyada zor se kyun aata hai?
Socho pehle… phir dekho jawab
Kyunki paani ka dabaav gehrai (oonchai ke farak) ke saath badhta hai. Tanki oonchi, phir nal tak paani ka stambh lamba, isliye nal par dabaav zyada — aur dhaar tez.
Pressure = thrust ÷ area. Thrust = kisi satah par seedha (perpendicular) lagne wala bal. SI unit: pascal (Pa) = 1 newton per square metre. Isliye patli dhaar wala chaaku kaatta hai, aur bhaari truck ke kai pahiye uska wazan sadak par failate hain.
Liquid ka dabaav: paani bartan ki tali aur deewaron par dabaav daalta hai, aur gehrai ke saath yeh badhta hai. Ek hi gehrai par har disha mein dabaav barabar. Isliye neeche ki dhaar door jaati hai, aur paani ki tanki oonchai par rakhi jaati hai.
Vayumandaliya dabaav (atmospheric pressure): hawa ka bhi wazan hai. Hum hawa ke samundar ki tali par rehte hain. Rubber sucker deewar par isliye chipakta hai kyunki andar se hawa nikal gayi aur bahar ki hawa use dabati hai.
Humne kya kiya :- Pressure ka formula, paani ki gehrai aur hawa ke dabaav ko roz ki cheezon — chaaku, tanki, sucker — se joda.
Isse kya hua :- Samjhe ki pressure area aur gehrai par tika hai; isi se tanki, pahiye aur aage baandh ka design tay hota hai.
Ghar pe try karo
Teen chhed wali bottle (bade chhed karein, tape se band) bharo, aangan mein ek ooncha patthar rakh kar us par khadi karo, tape hatao aur teeno dhaaron ki doori skale se naapo. Phir bottle aadhi bhar kar dohraao. Table banao: chhed, doori (poori bhari), doori (aadhi bhari). Paani paudhon ko do.
Wow!
6,000 metre gehre samundar mein paani ka dabaav hawa ke dabaav se lagbhag 600 guna hota hai — har 10 metre par lagbhag ek vayumandal jitna badhta hai!
3 sawaal
- Pressure ka SI unit kya hai?
Jawab dekho
Pascal (N/m²). Pressure = thrust ÷ area; unit N/m², jise pascal (Pa) kehte hain.
- Paani ki tanki chhat par kyun rakhi jaati hai?
Jawab dekho
Oonchai se nal tak paani ka dabaav badhta hai. Paani ka dabaav gehrai (oonchai ke farak) ke saath badhta hai, isliye oonchi tanki se nal mein tez dhaar aati hai.
- Rubber sucker deewar se kyun chipakta hai?
Jawab dekho
Andar hawa kam, bahar ki hawa ka dabaav use dabata hai. Sucker dabaane par andar ki hawa nikal jaati hai; bahar ka vayumandaliya dabaav use deewar se chipka deta hai.
NCERT se jodo: NCERT Class 8 Science — force aur pressure: liquid aur gas ka dabaav, vayumandaliya dabaav (idea in words)