Umsebenzi owenziwe ngamandla alondolozayo Amandla angenzeka
Buka into ehamba iqonde phezulu bese ibuyela endaweni yayo yokuqala ngemva kokufinyelela ukuphakama okuphezulu. Lapho into ihamba iqonde phezulu, isisindo senza umsebenzi ongemuhle entweni. Lapho into ihambela phezulu, ukuphakama kwento kuyanda. Ngakho-ke, amandla adonsela phansi ento nawo ayanda. Kungaphethwa ngokuthi umsebenzi ongemuhle owenziwe ngesisindo ulingana nokwenyuka kwamandla adonsela phansi ento (PE).
W = – mgh
W = – mg (h2 - h1) = – (PE2 – I-PE1) = -ΔPE
Uma into ihamba iqonde phansi, amandla adonsela phansi enza umsebenzi omuhle entweni. Uma into ihamba iqonde phansi, ukuphakama kwento kuyehla. Ngakho-ke, amandla adonsela phansi ento nawo ayancipha. Kungaphethwa ngokuthi umsebenzi omuhle owenziwa amandla adonsela phansi entweni ulingana nokwehla kwamandla adonsela phansi entweni.
W = mgh
W = mg (h1 - h2) = mgh1 – mgh2 = – (mgh2 – mgh1) = – (PE2 – I-PE1) = -ΔPE
Bheka into ecindezelwe ngakwesobunxele kanye nokuphela kwesiphethu (bheka isithombe 3). Lapho into ihamba ngakwesobunxele, amandla esiphethu enza umsebenzi ongemuhle entweni. Lapho into ihamba ngakwesobunxele, ukuphambuka kwentwasahlobo kuyanda. Ngakho-ke, amandla entwasahlobo nawo ayanda. Kungaphethwa ngokuthi umsebenzi ongemuhle owenziwe isiphethu ulingana nokwanda kwamandla entwasahlobo. Lapho into ihamba ngakwesokunene, amandla esiphethu enza umsebenzi omuhle entweni. Lapho into ihamba ngakwesokunene, ukuphambuka kwentwasahlobo kuyancipha. Ngakho-ke, amandla entwasahlobo nawo ayancipha. Kungaphethwa ngokuthi umsebenzi omuhle owenziwe isiphethu entweni ulingana nokwehla kwamandla entwasahlobo.
Ngokusho kwencazelo engenhla, kungashiwo ukuthi umsebenzi owenziwa amandla alondolozayo ulingana noshintsho emandleni angase abe khona ento. Lapho amandla alondolozayo enza umsebenzi omuhle, amandla angase abe khona ayancipha. Ngokuphambene nalokho, lapho amandla alondolozayo enza umsebenzi omubi, amandla angase abe khona ayanda. Ngakho-ke, umsebenzi owenziwa amandla alondolozayo ulingana noshintsho olungeluhle emandleni angase abe khona.
Wc = -ΔPE
Isibonelo sombuzo 6: Umsebenzi ngamandla alondolozayo kanye namandla angase abe khona
Into enesisindo esingu-1 kg iphakeme ngamamitha ama-5 ngaphezu komhlabathi. Ukusheshisa kwamandla adonsela phansi kungu-10 m/s2. Nquma (a) umsebenzi owenziwe ngesisindo lapho into isuswa iye ekuphakameni kwamamitha ayi-10 ngaphezu komhlabathi, (b) umsebenzi odingekayo ukuze into isuswe iye ekuphakameni kwamamitha ayi-10, kanye (c) noshintsho emandleni adonsela phansi ento lapho into isuswa iye ekuphakameni kwamamitha ayi-10.
Ingxoxo:
Kuhlonziwe: m = 1 kg, g = 10 m/s2 ,
(a) Sebenza ngesisindo
W = – mg Δh
= – (1 kg)(10 m/s2)(5 m) = – 50 amaJoule
Isisindo senza umsebenzi ongemuhle ngoba isiqondiso sesisindo siphambene nesiqondiso sokufuduka kwento.
(isisindo sisezansi, ukufuduka kwento kusezansi).
(b) Umsebenzi ngamandla okuphakamisa
Ukuze into ikwazi ukuphakanyiswa, amandla amancane okuphakamisa kumele alingane nesisindo.
= (1 kg)(10 m/s2)(5 m) = 50 amaJoule
W = wh = mg Δh
Umsebenzi owenziwe amandla okuphakamisa muhle njengoba isiqondiso samandla sifana nokufuduka.
(ukuphakanyiswa kwamandla kuqonde phezulu, ukufuduka kuqonde phezulu)
(c) Ushintsho emandleni angaba khona
ΔPE = mg Δh
ΔPE = 50 Joule
Amandla adonsela phansi ento anda ngama-Joules angu-50.
Imibuzo nezimpendulo ezingu-20 eziphathelene nomsebenzi owenziwa amandla alondolozayo kanye namandla angaba khona:
1. Umbuzo: Ayini amandla okugcina izinto ngendlela ehlelekile? Impendulo: Amandla okulondoloza amandla lapho umsebenzi owenziwe uzimele endleleni ethathiwe.
2. Umbuzo: Umsebenzi owenziwa amandla alondolozayo uhlobene kanjani noshintsho lwamandla angaba khona? Impendulo: Umsebenzi owenziwa amandla alondolozayo ulingana noshintsho olubi emandleni angaba khona.
3. Umbuzo: Shano isibonelo esivamile samandla alondolozayo. Impendulo: Amandla adonsela phansi ayisibonelo esivamile samandla alondolozayo.
4. Umbuzo: Kungani ukungqubuzana kungabhekwa njengamandla alondolozayo? Impendulo: Ngoba umsebenzi owenziwa ngokungqubuzana uncike endleleni ethathiwe.
5. Umbuzo: Amandla adonsela phansi ento eseduze nobuso boMhlaba abonakaliswa kanjani? Impendulo: Amandla adonsela phansi avezwa njenge ℎ, lapho u-m eyisisindo, u-g uyisivinini esibangelwa amandla adonsela phansi, kanti u-h uyikuphakama ngaphezu kwephuzu lokubhekisela.
6. Umbuzo: Ingabe amandla angaba khona angaba mabi? Impendulo: Yebo, amandla angaba khona angaba mabi kuye ngokuthi ukhetha yiphi indawo yokubhekisela.
8. Umbuzo: Uma amandla angase abe khona ohlelweni enyuka, kwenzekani kumandla e-kinetic, uma sithi akukho msebenzi wangaphandle owenziwe? Impendulo: Amandla e-kinetic ancipha ngenani elifanayo namandla angase akhule, okugcina ukulondolozwa kwamandla emishini.
9. Umbuzo: Yiziphi izimo zokulondolozwa kwamandla emishini? Impendulo: Amandla emishini alondolozwa uma amandla alondolozayo kuphela esebenza ohlelweni.
10. Umbuzo: Esimisweni esivaliwe lapho kusebenza khona amandla alondolozayo kuphela, yini engashiwo ngamandla aphelele omshini? Impendulo: Amandla aphelele okusebenza kwemishini ahlala engaguquki.
11. Umbuzo: Amandla angaba khona okushaja kagesi ensimini kagesi anqunywa kanjani? Impendulo: Amandla angaba khona , lapho u-q kuyishaji kanti u-V kuyikhono.
12. Umbuzo: Kungani ukuphakamisa into ensimini yamandla adonsela phansi kwandisa amandla ayo angaba khona? Impendulo: Ngoba umsebenzi wenziwa ngokumelene namandla adonsela phansi okuphakamisa into, egcinwa njengamandla angase abe khona.
13. Umbuzo: Umsebenzi wenziwa kanjani ngamandla alondolozayo ngendlela evalekile? Impendulo: Umsebenzi we-net owenziwe ngamandla alondolozayo phezu kwe-closed loop awukho.
14. Umbuzo: Amandla angase abe khona ahlobene kanjani nokuzinza? Impendulo: Ezindaweni lapho amandla angaba khona ephansi khona, uhlelo luhlala luzinzile.
15. Umbuzo: Ingabe izinto ezimbili eziphakeme ezihlukene zingaba namandla afanayo adonsela phansi? Impendulo: Yebo, bangakwazi, kuye ngokuthi kukhethwa izinga lokubhekisela lamandla angaba khona.
16. Umbuzo: Kungani sivame ukukhetha umhlabathi njengendawo yokubhekisela yamandla adonsela phansi? Impendulo: Inikeza inkomba elula neqondakalayo, yize noma yiliphi iphuzu lingakhethwa.
17. Umbuzo: Esimisweni esihlukanisiwe esinamandla okulondoloza kuphela, uma amandla angaba khona ehla ngo-10 J, amandla e-kinetic ashintsha kangakanani? Impendulo: Amandla e-kinetic akhuphuka ngo-10 J.
18. Umbuzo: Amandla angase abe khona ahlobene kanjani namandla emikhakheni yokulondoloza? Impendulo: Amandla ayi-gradient engemihle yamandla angase abe khona.
19. Umbuzo: Uma into ishukunyiswa iye ohlangothini lwamandla alondolozayo, amandla ayo angashintsha kanjani? Impendulo: Amandla ayo angase abe khona ayancipha.
20. Umbuzo: Kungenzeka yini ukuthi into ibe namandla e-kinetic kodwa ingabi namandla akhona? Impendulo: Yebo, kuncike ekukhetheni indawo yokubhekisela yamandla angaba khona.
Le mibuzo nezimpendulo zimboza imiqondo eyisisekelo mayelana namandla alondolozayo kanye namandla angaba khona, akha ingxenye ebalulekile yezindlela zakudala.
