Pawa

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Muchidzidzo fundoyetsimba, Pawa (Power) izwi rinodudzira kuitwa kwebasa paumwe hwechiyero chenguva. Pawa inopimwa nechiyero chinonzi Watt kana kuti (Joules/Second). Kana takatarisa mwenje wegetsi yakanyorwa kunzi 100Watts umwe 50Watts, kureva kuti mwenje wokutanga unoshandisa simba remagetsi rakapwetwa kaviri zvichienzaniswa nemwenje wechipiri. Uye tikatora varume vaviri wokutanga asenga masaga 50 echibage pama hour 4, wepiri akasenga masaga echibage 50 pamaawa 6 - wekutanga anenge ashanda nepawa rakakura pane wepiri.

Kushandurwa kwesimba kunogona kushandiswa kuita basa saka pawa inogonawo kurehwa sehuyero hwemudida (rate) wekuita basa. Basa rakafanana rinogona kuitwa nemunhu anokwira masitepusi akatakura saga rehupfu zvisinei kuti amhanya kana kuti afamba here, asi pawa yakawandiswa inoshandiswa pakumhanya nekuti basa racho rinoitwa munguva ishoma kupfura kana munhu wacho akamhanya.

Chiyero[chinja | edit source]

Ansel Adams photograph of Electrical Wires of the Boulder Dam Power Units
Mufananidzo waAnsel Adams wemawaya emagetsi eBoulder Dam Power Units, 1941-1942.

Nzenda (dimension) yepawa isimba kugova pana nguva. Chiyerwo muSI iWatt, yakatsazana neJoule rimwe pasekondi. Zvimwewo zviyero zvepawa zvinosanganisirawo masimbabhiza (horsepower), mafoot-pounds pamineti, nemakarori (calorie) paawa anoshandiswa munezvekudya. Simbabhiza rimwe rakaenzana nema33 000 foot-pounds pamineti zvakaenzanawo nemawatt 746.

Pawa mumaSisitemu eChimakanika[chinja | edit source]

Pawa mumasisitemu echimakanika (mechanical systems) isanganisiro yemafosi nehusuduruka. Chikuru, pawa maunga mhande efosi inoshanda pachinhu nemuchacha hwechinhu ichocho, kana kuti maunga mhande etoki (torque) pachiro chakaoma (rigid body) negonya muchacha (angular velocity) hwechiro ichocho.

Pawa mumakanika inokwanisawo kutsanangurwa setoredzero yebasa munguva (time derivative of work). Muzvemamakanika (mechanics), basa rinoitwa ne fosi F pachiro chinenge chichifamba munzira yakakombwa (curved path) C inopihwa neindegira pamutsetse (line integral):

W_C = \int_{C} \bold{F} \cdot \mathrm{d}\bold{x} = \int_{C}\bold{F}\cdot \bold{v}dt,

panova x iri nzira C ne v uri muchacha munzira iyi. Toredzero munguva yetsazaniso yebasa inopa pawa panguva imwe se:

P(t) = \mathbf{F}\cdot \mathbf{v} .

Mumasisitemu anoziririka, pawa huunga mhande hwetoki τ negonya muchacha ω,

P(t) = \mathbf{\tau} \mathbf{\omega}, \,

panova ω inoyerwa muma redhieni pasekondi.

Pawa muMagetsi[chinja | edit source]

Pawa yemagetsi inopihwa kune michina kana chinhu chinoshanda nemagetsi pane nguva imwe chete inowanikwa netsazaniso inoti


P(t) = I(t) \cdot V(t) \,

pachiva ne

  • P(t) sepawa panguva imwe chete inoyerwa mumaWatts (Joules/Second),
  • I(t) rufuvha rwemagetsi (Current) runoyerwa nemaAmperes,
  • V(t) sebasa paumwe hwechaji (Voltage) rinoyerwa nemaVolts.

Kana kamuchina kanenge kachishandiswa kari rizisita (resistor) inenge ine resho yebasa paumwe hwechaji kunerufuvha isingachinje, zvinotevera kuti:


P=I \cdot V = I^2 \cdot R = \frac{V^2}{R} \,

pane


R = V/I \,

iriyo mukweso hunoyerwa mumaohm.