Izinto Zokucindezela Koketshezi
Ku-physics, ingcindezi ichazwa njengamandla endaweni ngayinye, lapho isiqondiso samandla siqonde endaweni engaphezulu. Ngokwezibalo, ingcindezi ivezwa yi-equation P = F/A, lapho u-P = ingcindezi, u-F = amandla kanye no-A = indawo engaphezulu. Iyunithi yamandla (F) yi-Newton (N), iyunithi yendawo ingamamitha-skwele (m 2 ). Njengoba ingcindezi ingamandla endaweni ngayinye, iyunithi yokucindezela yi-N/m 2. Elinye igama le-N/m 2 yi-pascal (Pa). I-Pascal isetshenziswa njengeyunithi yokucindezela ukuhlonipha uBlaise Pascal.
Uma uketshezi luphumulile, lusebenzisa amandla aqonde ngqo kuyo yonke indawo oluthintana nayo. Isibonelo, cabanga ngamanzi asengilazini; ingxenye ngayinye yamanzi inamandla aqonde ngqo odongeni lwengilazi. Ngakho-ke, ingxenye ngayinye yamanzi inamandla aqonde ngqo endaweni ngayinye yeyunithi yesitsha esihlala kuyo. Lokhu kuyisici esibalulekile soketshezi olungaguquki, uketshezi oluphumulile. Uma uketshezi lusebenzisa amandla phezu kwendawo, lapho amandla engekho aqonde ngqo, ubuso buzosebenzisa amandla okusabela, futhi hhayi aqonde ngqo. Lokhu kuzokwenza ukuthi uketshezi lugeleze. Kodwa-ke, empeleni, uketshezi luhlala luphumulile. Ngakho-ke, oketshezini oluphumulile, amandla ahlala eqonde ngqo phezu kwesitsha esihlala kuso.
Esinye isici esibalulekile soketshezi oluphumulile ukuthi luhlala lucindezela kuzo zonke izinhlangothi. Ukuze uqonde kangcono lokhu, beka into entantayo esitsheni samanzi. Uma amanzi engashintshi ngokuphelele, into izohlala ingashintshi ngoba ingcindezi esetshenziswa ebusweni bayo bonke ilingana. Uma ingcindezi yamanzi ingalingani, kuzoba namandla aphelele, azokwenza into inyakaze.
Umphumela wokujula ekucindezelekeni
Ukujula noma ukuphakama kuyithinta kanjani ingcindezi yoketshezi? Ingabe ingcindezi yamanzi olwandle ekujuleni kwamamitha ayi-10 iyafana nengcindezi yamanzi olwandle ekujuleni kwamamitha ayi-100? Ake sicabangele ingcindezi yamanzi esitsheni njengoba kuboniswe esithombeni. Ukuphakama kwekholomu yoketshezi kungu-h kanti indawo yayo enqamulayo ingu-A. Iyini ingcindezi yamanzi phansi kwesitsha?
w = isisindo samanzi, h = ukuphakama kwekholomu yamanzi esitsheni esiyisilinda, A = indawo yobuso kanye no-P kuyingcindezi.
Imininingwane:
w = amandla adonsela phansi
ρ = ukuminyana
m = amasa
g = ukusheshisa ngenxa yamandla adonsela phansi
V = hA = ivolumu yekholomu yoketshezi (h = ukuphakama, A = indawo engaphezulu)
Uma siyifaka ku-equation yokucindezela, sithola:
p = ρ gh → Isibalo 1 (isitsha esivaliwe)
p = pa + ρ gh → Isibalo 2 (isitsha esivulekile)
Imininingwane:
i-pa = Ukucindezela komoya
ρ gh = Ukucindezela kwe-hydrostatic
Esithombeni esingenhla, ingcindezi yomoya ayiboniswa, kodwa empeleni, uma isitsha esinamanzi sivulekile, ingcindezi yomoya nayo izosebenza ebusweni bamanzi, aqondiswe phansi.
Ngokusekelwe ku-equation engenhla, kubonakala sengathi ingcindezi ilingana ngqo nobuningi kanye nokujula koketshezi (ukusheshisa kwamandla adonsela phansi kuhlala kungaguquki). Njengoba ukujula koketshezi kukhuphuka, ingcindezi nayo iyanda. Uketshezi cishe alukwazi ukucindezelwa ngenxa yesisindo soketshezi olungaphezu kwawo, ngakho-ke ubuningi boketshezi buhlala bungaguquki. Uma umehluko wokuphakama mkhulu kakhulu (isibonelo, emanzini ajulile kakhulu olwandle), ubuningi buyahlukahluka kancane. Kodwa-ke, uma umehluko wokuphakama ungemkhulu kakhulu, ubuningi boketshezi buyafana noma umehluko mncane kakhulu kangangokuthi unganganakwa.
Singasebenzisa futhi i-equation engenhla ukubala umehluko wokucindezela ekujuleni okuhlukene. I-equation engenhla ingabhalwa kabusha ngokuthi:
Ukucindezela Komoya
Uma sicwila ngaphansi kwamanzi, umzimba wethu wonke umbozwe ngamanzi. Lapho sicwila sijula, kulapho sizwa khona ingcindezi enkulu. Eqinisweni, nsuku zonke simbozwe nangumkhathi, ohlala ucindezela kuzo zonke izingxenye zomzimba wethu, njengalapho sicwila ngaphansi kwamanzi. Njengasemanzini olwandle, ubuso boMhlaba bungafaniswa "nolwandle" lomkhathi. Uma kuyiqiniso ukuthi umkhathi nawo ucindezela kuzo zonke izingxenye zomzimba wethu ngaso sonke isikhathi, kungani singawuzwa, njengokungathi sisezansi kolwandle? Amaseli omzimba wethu agcina ingcindezi yangaphakathi efana nengcindezi yangaphandle. Yingakho singayizwa imiphumela yalo mehluko wengcindezi.
Umfutho womhlaba nawo uyashintsha ngokuphakama. Kodwa-ke, umfutho womhlaba uyahluka kancane kunowoketshezi. Ushintsho ekubunjweni koketshezi luncane kakhulu uma kuqhathaniswa okuncane ngokujula, ngakho-ke ubuningi boketshezi bucatshangwa ukuthi buyafana. Lokhu kuhlukile ekubunjweni komoya womhlaba. Ubuningi bomoya womhlaba buhluka kakhulu ngokuphakama. Ubuningi bomoya ezindaweni ezahlukene buhlukile, ngakho-ke asikwazi ukubala umfutho womoya sisebenzisa i-equation ethathwe ngenhla. Ngaphezu kwalokho, akukho mngcele womoya ocacile lapho ukuphakama kungalinganiswa khona. Umfutho womoya nawo uyahlukahluka ngesimo sezulu. Ukuze sinqume umfutho womoya, sithatha izilinganiso.
Ukulinganisa Ukucindezela
U-Evangelista Torricelli (1608–1647), umfundi kaGalileo, wasungula indlela yokulinganisa ingcindezi yomoya ngo-1643 esebenzisa i-mercury barometer yakhe. I-barometer yayine-tube yengilazi ende egcwele i-mercury. I-tube yengilazi egcwele i-mercury yayiphendukezelwe esitsheni esasigcwele ne-mercury.
Uma ithubhu yengilazi equkethe i-mercury iphendulwa ibheke phansi, ingxenye engezansi yethubhu ayigcwali i-mercury, iqukethe kuphela umhwamuko we-mercury ongcindezi yawo incane kangangokuthi ayinakwa (p).2 = 0). Phezu kwe-mercury epuletini, kukhona ingcindezi yomoya eqondiswe phansi (umkhathi ucindezela i-mercury epuletini). Le ngcindezi yomoya isekela ikholomu ye-mercury eshubhu lengilazi. Esithombeni, ingcindezi yomoya ifanekiselwa yi-po Ubukhulu bomfutho womoya bungabalwa kusetshenziswa i-equation:
p o = ρ gh
Ngokusekelwe emiphumeleni yokulinganisa, ingcindezi evamile yomoya olwandle ingu-1,013 x 10 5 N/m 2. Ubukhulu bomfutho womoya olwandle busetshenziselwa ukuchaza enye iyunithi yokucindezela, okungukuthi i-atm (umkhathi). Ngakho-ke i-atm engu-1 = 1,013 x 10 5 N/m 2 = 101,3 kPa (kPa = kilo pascal). Enye iyunithi yokucindezela yi-bar (evame ukusetshenziswa ku-meteorology). Ibha engu-1 = 1,00 x 10 5 N/m 2 = 100 kPa.
Ingakanani ingcindezi yomoya engenhla etholakala?
Ukulinganisa kusebenzisa isimiso esiboniswe nguTorricelli ngenhla. Ukuphakama kwekholomu ye-mercury esetshenzisiwe kungu-76 cm (umfutho womoya ungasekela kuphela ikholomu ye-mercury engama-76,0 cm ukuphakama), lapho izinga lokushisa le-mercury esetshenzisiwe lingu-0 ngqo. oC futhi ubukhulu bokusheshisa kwamandla adonsela phansi buyi-9,8 m/s2. Ubuningi be-mercury kulesi simo bungu-13,6 x 103 kg / m3Ukucindezela komoya:
Isilinganiso sokucindezela
Kunamathuluzi amaningi asetshenziswa ukukala ingcindezi, kufaka phakathi i-manometer yepayipi elivulekile.
Ku-manometer yepayipi elivulekile, lapho ipayipi linomumo ongu-U, ipayipi ligcwele kancane uketshezi (i-mercury noma amanzi). Ingcindezi elinganisiwe ihlobene nomehluko wokuphakama okubili koketshezi olufakwe epayipini. Ingcindezi ibalwa kusetshenziswa i-equation:
Ngokuvamile, akuwona umkhiqizo we-ρ gh obalwa kodwa ukuphakama koketshezi (h) ngoba ingcindezi ngezinye izikhathi ivezwa ngamamilimitha e-mercury (mm hg) noma amamilimitha amanzi (mm H 2 O). Elinye igama le-mm hg yi-torr (ekukhumbuleni u-Evangelista Torricelli).
Ngaphandle kwama-manometer, kunezinye izinsimbi zokulinganisa, okungukuthi ama-barometer angasebenzisi i-aneroid, kokubili oomatshini kanye nogesi, okuhlanganisa ama-gauge okucindezela amathayi, njll. Ithuluzi elisetshenziswa uTorricelli ukukala ingcindezi yomoya libizwa nangokuthi i-mercury barometer, lapho ithubhu yengilazi igcwaliswa nge-mercury bese iguqulwa ibe yipuleti eliqukethe ne-mercury.
Ingcindezi Elinganisiwe, Ingcindezi Yesilinganiso kanye Nengcindezi Ephelele
Uma kugcwaliswa amathayi emoto ngomoya, kuvame ukusetshenziswa igeyiji yokucindezela komoya. Lokhu kuqinisekisa ukuthi ukucindezela kwethayi akuphansi kakhulu noma akuphakeme kakhulu. Uma kugcwaliswa amathayi ngomoya, kulinganiswa ukucindezela komoya okungaphakathi kwethayi kuphela. Ukucindezela komoya akucatshangelwa. Akukhona nje kuphela lapho kulinganiswa ukucindezela kwethayi, kodwa nakwezinye izilinganiso eziningi zokucindezela, ukucindezela komoya akulinganiswa. Lo kucindezela okulinganisiwe kubizwa ngokuthi ukucindezela okulinganisiwe. Ngakho-ke, uyini umehluko phakathi kwalokhu nokucindezela okuphelele?
Ukucindezela okuphelele = ukucindezela komoya + ukucindezela okulinganisiwe. Ngakho-ke ukuze sithole ukucindezela okuphelele, sengeza ukucindezela okulinganisiwe kungcindezi yomoya. Ngamanye amazwi, ukucindezela okuphelele = ukucindezela okuphelele. Ngokwezibalo, lokhu kungabhalwa kanje:
isilinganiso se-p = pa + p
Isibonelo, uma ingcindezi yethayi esiyilinganisayo = 100 kPa, khona-ke ingcindezi ephelele yile:
isilinganiso se-p = pa + p
p = 101 kPa + 100 kPa
p = 201 kPa
Ingcindezi ephelele = 201 kPa.
Kukhona elinye igama: ingcindezi yokulinganisa, eyaziwa nangokuthi ingcindezi yokulinganisa. Ingcindezi yokulinganisa ingcindezi eningi ngaphezu kwengcindezi yomoya. Isibonelo, cabanga ngengcindezi yethayi lesithuthuthu. Uma ithayi lesithuthuthu lincishisiwe, ingcindezi engaphakathi kwethayi ilingana nengcindezi yomoya (Ingcindezi yomoya = 1,01 x 105 Pa = 101 kPa). Uma ithayi ligcwele umoya, ingcindezi yethayi iyanda ngokwemvelo. Uma ingcindezi yethayi idlula i-101 kPa, ingcindezi eningi ibizwa nangokuthi ingcindezi yokulinganisa.
Imibuzo Yesibonelo Sokucindezela Koketshezi
Isibonelo sombuzo 1:
Umkhumbi-ngwenya ucwila ujule ngamamitha angu-200. Uyini umfutho obhekene nomkhumbi-ngwenya?
ukuntywila? g = 10 m/s2
Ingxoxo
Kuyaziwa ukuthi:
Ukujula (h) = 200 m
Ubuningi bamanzi olwandle (ρ) = 1,03 x 103 kg / m3 = 1030 kg / m3 (bheka ithebula lobuningi)
Umfutho womoya (pa) = 1 atm = 1 x 105 N / m2 = 1 x105 (Kg m/s2)/m2 = 1 x105 Amakhilogremu/ms2
Ukusheshisa ngenxa yamandla adonsela phansi (g) = 10 m/s2
Kubuziwe: Ingcindezi
Impendulo:
Isitsha sivulekile ngakho-ke umfutho womoya awufakiwe ekubalweni.
Isibonelo sombuzo 2:
Idamu lamanzi elingamamitha ayi-10 ukuphakama ligcwele amanzi. Uma ubuso bedamu lamanzi bugcwele amanzi.
ivaliwe, ingakanani ingcindezi yamanzi phansi kwesitsha? g = 10 m/s2
Ingxoxo
Kuyaziwa ukuthi:
Ukuphakama (h) = 10 m
Ubuningi bamanzi (ρ) = 1,00 x 103 kg / m3 = 1000 kg / m3
Umfutho womoya (pa) = 1 atm = 1 x 105 N / m2 = 1 x105 (kg m/s2) / m2 = 1 x105 Amakhilogremu/ms2
Ukusheshisa ngenxa yamandla adonsela phansi (g) = 10 m/s2
Kubuziwe: Ingcindezi
Impendulo:
Isitsha sivaliwe ngakho-ke umfutho womoya awufakiwe ekubalweni.
Isibonelo sombuzo 3:
Ukuphakama kwekholomu yamanzi (kwesokudla) = 50 cm, kanti ukuphakama kwenye ikholomu yoketshezi (kwesobunxele) = 30 cm. Kuyini ubuningi benye i-liquid?
Ingxoxo
Kuyaziwa ukuthi:
Ukusheshisa ngenxa yamandla adonsela phansi (g) = 10 m/s2
Izinga lamanzi (h1= 50cm
Ubuningi bamanzi (ρ)1) = 1,00 x 103 kg / m3 = 1000 kg / m3
Ukuphakama koketshezi okunye (h)2= 30cm
Ubuningi bezinye izinto eziwuketshezi (ρ)2) =?
pa + ρ 1 gh 1 = pa + ρ 2 gh 2
Umfutho womoya (Pa) kanye nokusheshisa kwamandla adonsela phansi (g) kuyafana, ngakho-ke kuyayeka ukusebenza.
Isibonelo sombuzo 4:
Ngaphakathi kwepayipi lengilazi kukhona uketshezi oluphakeme ngamasentimitha ayi-10. Umfutho wamanzi phansi kwepayipi ungu-1200 N/m2Uma g = 10 m/s2. Unganaki umfutho womoya. Kungakanani ubuningi boketshezi?
A. 800 kg/m3
B. 900 kg/m3
C. 1000 kg/m3
D. 1200 kg/m3
E. 1300 kg/m3
Ingxoxo:
I-Diketahui :
I-Ketinggian uketshezi (h) = 10 cm = 0,1 amamitha
Umfutho wamanzi (P) phansi kwepayipi = 1200 N/m2
Ukusheshisa Amandla Adonsela Phansi (g) = 10 m/s2
Kubuziwe :
Ubuningi uketshezi?
Jawab :
Ubuningi uketshezi luyi-1200 kg/m23.
Impendulo efanele ngu-D.
Isibonelo sombuzo 5:
I-Mercury emikhunjini exhunyiwe inomehluko wobuso obungu-3 cm. Ubuningi be-mercury = 13,6 gr/cm3Ukuphakama koketshezi epayipini ngakwesobunxele kungu-10 cm. Kungakanani ubuningi boketshezi?
A. 800 kg/m3
B. 1030 kg/m3
C. 1080 kg/m3
D. 1300 kg/m3
E. 1360 kg/m3
Ingxoxo:
I-Diketahui :
Ukuphakama (h) kweMercury = 3 cm = 0,03 m
Ubuningi be-mercury = 13,6 gr/cm3 = 13600 kg / m3
Ukuphakama (h) koketshezi = 10 cm = 0,1 m
Kubuziwe :
Ubuningi uketshezi?
Impendulo:
Uhlelo lusesimweni sokulingana okungaguquki ngakho-ke ukucindezela koketshezi (ithubhu yesobunxele) = ingcindezi ye-mercury (ithubhu yesokudla)
Pumoya +Puketshezi =Pumoya +Pi-mercury
Umfutho womoya uyafana ngakho-ke uyasuswa kulesi sibalo
uketshezi lwe -P = umoya we-P
Impendulo efanele ngu-C.
