Ibhizinisi lefiziksi

Uma ucindezela incwadi etafuleni ize ihambe, usuke wenza umsebenzi encwadini. Uma into iwela ebusweni bomhlaba ngoba idonswa amandla amandla adonsela phansi Amandla adonsela phansi omhlaba asebenza entweni. Ngokuphambene nalokho, uma ucindezela into ngamandla akho onke uze ujuluke kodwa into ingashukumi, awukasebenzi kuyo. Empilweni yansuku zonke, kuthiwa wenze umsebenzi noma usebenze kanzima ucindezela into, kodwa ngokwesayensi, awukasebenzi entweni ngoba into ayishukumi (ayikashukumi).

Ibhizinisi kungenziwa ngamandla angaguquki (ubukhulu kanye nesiqondiso samandla kuhlala kufana) noma amandla aguquguqukayo (ubukhulu kanye nesiqondiso samandla kuyashintsha). Isibonelo samandla anobukhulu kanye nesiqondiso esingaguquki amandla adonsela phansi asebenza entweni eseduze nobuso boMhlaba. Isibonelo samandla anobukhulu kanye nesiqondiso esingaguquki amandla esiphethu. Uma welula isiphethu, lapho usilula kakhulu, kulapho usidonsa kanzima, ngakho-ke ubukhulu bamandla abuguquki njengoba isiphethu sinwebeka. Esinye isibonelo yilapho irokhethi lingena emkhathini, lapho likude kakhulu nobuso boMhlaba, kulapho lincane khona amandla adonsela phansi oMhlaba asebenza erokhethini.

1.1 Umsebenzi owenziwa ngamandla aqhubekayo
Ngokwezibalo, umsebenzi owenziwa amandla angaguquki entweni uwumphumela ukufuduka into enamandla noma ingxenye yamandla esendleleni efanayo nokufuduka kwento.

Umsebenzi owenziwe ngamandla asunduzayo (F):
W = (F)(s)(cos θ) = F s (cos 0) = F s (1) = F s
Umsebenzi owenziwe yisakhi samandla u-F ohlangothini oluvundlile (F cos θ):
W = (F cos θ)(s)(cos 0) = (F cos θ)(ama)(1) = F s cos θ
Umsebenzi owenziwe ngamandla okungqubuzana kwe-kinetic (fk):
W = (f_k cos θ(s)(cos 180) = (f_k )(s)(-1) = – f_k s
Umsebenzi owenziwe ngamandla avamile (N):
W = (N)(s)(cos 90^o) = (N)(s)(0) = 0
Umsebenzi owenziwe ngamandla adonsela phansi (w):
W = (w)(s)(cos 90^o) = (w)(s)(0) = 0
Incazelo: W = umzamo noma umsebenzi (amaJoules), s = ukufuduka (amamitha), θ = i-engeli eyakhiwe ngamandla ngokufuduka

Esibonelweni esidlule, umsebenzi owenziwe ngu- amandla adonsela phansi (w) inenani elingu-zero ngoba isiqondiso samandla adonsela phansi siqondile (sakha i-engeli engu-90°)^o) ngesiqondiso sokufuduka (isiqondiso sokunyakaza) sento. Kufanele kuqashelwe ukuthi umsebenzi owenziwe yisisindo awusi-zero uma isiqondiso samandla adonsela phansi sifana noma siphambene nesiqondiso sokufuduka.

Umsebenzi owenziwe ngamandla adonsela phansi (w) entweni ewa ngokukhululeka esithombeni a uthi:
W = F s (cos θ) = wh (cos 0) = wh (1) = wh = mgh
Umsebenzi owenziwe ngamandla adonsela phansi (w) entweni ehamba phezulu phezulu kumfanekiso b uthi:
W = F s (cos θ) = wh (cos 180) = wh (-1) = -wh = -mgh

Incazelo: w = isisindo (Newton), h = ukuphakama (amamitha), m = isisindo (kg), g = ukusheshisa ngenxa yamandla adonsela phansi (amamitha ngomzuzwana ayisikwele)

Ngokusekelwe encazelweni yangaphambilini, amaphuzu alandelayo angaphethwa:
I-Pertama, uma into ingahambi, khona-ke amandla asebenza ekuhambeni awasebenzi. Uma u-s = 0 khona-ke u-W = 0.
I-KeduaUma amandla akha i-engeli ethile ekufudukeni kwento, khona-ke ingxenye yamandla kuphela ebheke ekufudukeni kwento esebenza entweni.
I-Ketiga, amandla aqondene nokususwa kwento awenzi msebenzi entweni. Uma amandla eqondene nokususwa, i-engeli eyakhiwe ingu-90°^o. I-Cos 90^o = 0.
Okwesine, Umzamo ungaba muhle noma mubi. Uma amandla esendleleni efanayo nokufuduka kwento, i-engeli eyakhiwe ingu-0^o khona-ke amandla enza umsebenzi omuhle, ngokuphambene uma amandla ephambene nokushintsha ngakho i-engeli eyakhiwe ingu-180^o bese amandla enza umsebenzi ongemuhle entweni.
Umsebenzi owenziwa amandla angaguquki entweni ngenkathi into ibhekana nokufuduka ulingana nendawo enomthunzi kugrafu yamandla (F) kanye nokufuduka (s).
Uphawu lomsebenzi ngu-W (uhlamvu olukhulu) kanti uphawu lwesisindo ngu-w (uhlamvu oluncane). Iyunithi yesistimu yomhlaba wonke yomsebenzi yi-Newton meter (N m). Elinye igama le-Newton meter yi-Joule, efushanisiwe ngu-J, eqanjwe ngokuhlonipha isazi sesayensi saseBrithani sekhulu le-19 uJames Prescott Joule.

1.2. Umsebenzi owenziwe ngamandla angaguquki
Isibonelo esisodwa samandla aguquguqukayo amandla entwasahlobo. Ubukhulu bamandla entwasahlobo buhlala bushintsha, ngakho-ke umsebenzi owenziwe amandla entwasahlobo entweni awukwazi ukubalwa kusetshenziswa ifomula yomsebenzi owenziwe amandla angaguquki.

Uma intwasahlobo inwetshiwe, uma intwasahlobo isinde, kulapho kudingeka amandla amakhulu. Ngokufanayo, ngokuphambene nalokho, uma ingcindezi icindezelwa kakhulu, amandla amafushane uma intwasahlobo injalo, kulapho kudingeka amandla amakhulu. Uma nje intwasahlobo icindezelwa noma inwetshiwe, amandla entwasahlobo ashintsha kusuka ku-0 (x = 0) kuya ku-maximum (F = kx) ngakho amandla entwasahlobo abalwa kusetshenziswa isilinganiso. Amandla entwasahlobo ajwayelekile yilawa:
F = ½ (0 + kx) = ½ kx
Umsebenzi owenziwa amandla esiphethu entweni uthi:
W = F x = ½ kx²
Incazelo: W = umsebenzi (amayunithi amaJoules), x = ukwanda kobude bentwasahlobo (amayunithi amamitha), F = amandla entwasahlobo (amayunithi iNewton).

2. Umsebenzi ophumelelayo noma umsebenzi ophelele (umsebenzi owenziwe ngamandla aphelele)
Uma kukhona amandla asebenza entweni ngesikhathi sokuhamba kwayo, khona-ke umsebenzi owenziwe amandla aphelele ulingana nomsebenzi owenziwe yilawo mandla. Isibonelo, lapho into ikwi-free fall futhi ukumelana nomoya kunganakwa, amandla asebenza entweni kuphela amandla adonsela phansi.
W= W_{amandla adonsela phansi}
Uma kukhona amandla amaningana asebenza entweni ngenkathi into ihamba, khona-ke umsebenzi owenziwe amandla aphelele ulingana nesamba somsebenzi owenziwe yiwo wonke amandla asebenza entweni.
W = W₁ + UW₂ + UW₃ + … + W_n
Umsebenzi owenziwa amandla amaningana asebenza entweni ungabalwa ngokuthola kuqala ubukhulu bamandla aphelele bese uwaphindaphinda ngobukhulu bokufuduka.
W = (Amandla omphumela)(ukufuduka) = (umphumela F(s)

Ireferensi