1. Umuntu udonsa ibhlogo elingamamitha amabili endaweni evundlile ngamandla angaguquki F = 20 N. Thola umsebenzi owenziwe ngamandla F osebenza kubhlogo.
Kwaziwa:
Amandla (F) = 20 N
Ukufuduka (s) = 2 m
I-engeli (θ ) = 0
Okufunwayo : Umsebenzi (W)
Isixazululo:
W = F d cos θ = (20)(2)(cos 0) = (20)(2)(1) = 40 Joule
2. Amandla F = 10 N asebenza ebhokisini eliyi-1 m eduze kwendawo evundlile. Amandla asebenza nge-engeli engama-30 o njengoba kuboniswe esithombeni esingezansi. Thola umsebenzi owenziwe ngamandla F!
Kwaziwa :
Amandla (F) = 10 N
Amandla avundlile (F x ) = F cos 30 o = (10)(0.5√3) = 5√3 N
Ukufuduka (d) = 1 imitha
Ufunwa : Umsebenzi (W)?
Isixazululo :
W = F x d = (5√3)(1) = 5√3 AmaJoules
3. Umzimba uwela ngokukhululeka ekuphumuleni, kusukela ekuphakameni kwamamitha amabili. Uma ukusheshisa ngenxa yamandla adonsela phansi kungu-10 m/s 2 , nquma umsebenzi owenziwe ngamandla adonsela phansi!
Kwaziwa:
Isisindo sento (m) = 1 kg
Ukuphakama (h) = 2 m
Ukusheshisa ngenxa yamandla adonsela phansi (g) = 10 m/s 2
Okufunwayo: Umsebenzi owenziwe ngamandla adonsela phansi (W)
Isixazululo:
W = F d = wh = mgh
W = (1)(10)(2) = 20 amaJoule
W = umsebenzi, F = amandla, d = ibanga, w = isisindo , h = ukuphakama, m = isisindo, g = ukusheshisa ngenxa yamandla adonsela phansi.
4. Into enesisindo esingu-1 kg inamathele esiphethwini ukuze inwetshwe ngo-2 cm. Uma ukusheshisa ngenxa yamandla adonsela phansi kungu-10 m/s 2 , nquma (a) i-spring constant (b) umsebenzi owenziwe ngamandla esiphethwini entweni
Kwaziwa:
Isisindo (m) = 1 kg
Ukusheshisa ngenxa yamandla adonsela phansi (g) = 10 m/s 2
Ubude (x) = 2 cm = 0.02 m
Isisindo (w) = mg = (1 kg)(10 m/s 2 ) = 10 kg m/s 2 = 10 N
Okufunwayo: I-Spring constant kanye nomsebenzi owenziwe yi-spring force
Isixazululo:
(a) I-constant yasentwasahlobo
Ifomula yomthetho kaHooke :
F = k x.
k = F / x = w / x = mg / x
k = (1)(10) / 0.02 = 10 / 0.02
k = 500 N/m
(b) umsebenzi owenziwe ngamandla entwasahlobo
W = – ½ kx 2
W = – ½ (500)(0.02) 2
W = – (250)(0.0004)
W = -0.1 Joule
Uphawu lokususa lubonisa ukuthi isiqondiso samandla entwasahlobo siphambene nesiqondiso sokufuduka kwento.
5. Amandla F = 10 N asheshisa ibhokisi phezu kokuhamba okungu-2 m. Iphansi liqinile futhi linamandla okungqubuzana F k = 2 N. Thola umsebenzi wenethi owenziwe ebhokisini.
Kwaziwa:
Amandla (F) = 10 N
Amandla okungqubuzana kwe-kinetic (F k ) = 2 N
Ukufuduka (d) = 2 m
Okufunwayo: Inethiwekhi (i-W net )
Isixazululo:
Umsebenzi owenziwe ngenkani F:
W 1 = F d cos 0 = (10)(2)(1) = 20 amaJoules
Umsebenzi owenziwe ngamandla okungqubuzana kwe-kinetic (F k ):
W 2 = F k d = (2)(2)(cos 180) = (2)(2)(-1) = -4 AmaJoules
Inethiwekhi:
I-W inethi = W 1 – W 2
I-W inethi = 20 – 4
I-W inethi = 16 Joule
6. Uyini umsebenzi owenziwe ngenkani u-F ebhlokini?
Kwaziwa:
Amandla (F) = 12 Newton
Ukufuduka (d) = amamitha angu-4
Okufunwayo: Umsebenzi (W)
Isixazululo:
W = F d = (12 Newton)(amamitha angu-4) = 48 N m = 48 Joules
7. Ibhlokhi licindezelwa ngamandla angu-200 N. Ukuhamba kwebhlokhi kungamamitha ama-2. Uyini umsebenzi owenziwayo ebhlokhini?
Kwaziwa:
Amandla (F) = 200 Newton
Ukufuduka (d) = amamitha angu-2
Okufunwayo: Umsebenzi (W)
Isixazululo:
Umsebenzi:
W = F s
W = (200 Newton)(amamitha ama-2)
W = 400 N m
W = 400 Joule
8. Umshayeli we-sedan ufuna ukupaka imoto yakhe ngqo phambi kweloli elingamamitha ayi-0.5, okuyimitha eyi-10 ukusuka endaweni ye-sedan. Yimuphi umsebenzi odingwa yi-sedan?
Kwaziwa:
Ukufuduka (d) = amamitha ayi-10 – amamitha angu-0.5 = amamitha angu-9.5
Amandla (F) = 50 Newton
Okufunwayo: Umsebenzi (W)
Isixazululo:
W = F s
W = (50 Newton)(amamitha ama-9.5)
W = 475 N m
W = 475 Joule
9.
Umsebenzi owenziwe nguTom noJerry ukuze imoto ikwazi ukuhamba ibanga elingafika kumamitha angu-4. Amandla asetshenziswa nguTom noJerry angama-50 N kanye nama-70 N.
Kwaziwa:
Ukufuduka (ama) = amamitha angu-4
Amandla aphelele (F) = 50 Newtons + 70 Newtons = 120 Newtons
Okufunwayo: Umsebenzi (W)
Isixazululo:
W = F s = (120 Newton)(4 amamitha) = 480 N m = 480 Joules
10. Umshayeli udonsa imoto ukuze imoto ihambe ibanga elingafika ku-1000 cm. Yini eyenziwayo emotweni?
Kwaziwa:
Amandla (F) = 250 Newton
Ukufuduka (ama) = 1000 cm = 1000/100 amamitha = 10 amamitha
Okufunwayo: Umsebenzi (W)
Isixazululo:
W = F s = (250 Newton)(10 amamitha) = 2500 N m = 2500 Joules
11. Ngokusekelwe esithombeni esingezansi, uma umsebenzi owenziwe ngamandla e-net ungama- Joules angu-375, nquma ukufuduka kwento.
Kwaziwa:
Umsebenzi (W) = 375 Joule
Amandla engqikithi ( ΣF) = 40 N + 10 N – 25 N = 25 Newtons ( kwesokudla )
Kufunwa: Ukufuduka ( d )
Isixazululo:
Isilinganiso somsebenzi:
W = F s
Ukufuduka kwento:
d = W / F = 375 Joules / 25 Newtons
d = amamitha ayi-15 s
12. Imisebenzi engezansi engasebenzi yilena …
A. Cindezela into kuze kufike kumamitha ayi-10
B. Cindezela imoto ize ihambe
C. Cindezela udonga
D. Wadonsa ibhokisi
Isixazululo:
Isilinganiso somsebenzi:
W = ΣF s
W = umsebenzi , F = amandla , d = ukufuduka
Ngokusekelwe kufomula engenhla, umsebenzi wenziwa ngenkani futhi kukhona ukufuduka.
Impendulo efanele ithi C.
1 3. U-Andrew usunduza into ngamandla angu-20 N ukuze into ihambe ngokunyakaza okujikelezayo okunerediyasi yamamitha angu-7. Thola umsebenzi owenziwe ngu-Andrew wokunyakaza okujikelezayo okuphindwe kabili.
A. 0 Joule
B. 1400 Joule
C. 1540 Joule
D. 1760 Joule
Isixazululo:
Uma umuntu esunduza isihlalo sabakhubazekile ukunyakaza okuphindwe kabili, umuntu kanye nesihlalo sabakhubazekile babuyela endaweni yokuqala, ngakho-ke ukugudluzwa komuntu kungu-zero.
Ukufuduka = 0 ngakho-ke umsebenzi = 0.
Impendulo eyiyo ngu-A.
14. Othile usunduza into phansi ngamandla angu-350 N. Iphansi linamandla okungqubuzana angu-70 N. Thola umsebenzi owenziwe ngamandla ukuze uhambise into kude kufike kumamitha ayi-6.
A. 45 J
B. 72 J
C. 1680 J
D. 2580 J
Kwaziwa:
Amandla okusunduza (F) = 350 Newtons
Amandla okungqubuzana (F fric ) = 70 Newtons
Ukufuduka kwento (izinto) = amamitha ayi-6
Okufunwayo: Umsebenzi (W)
Isixazululo:
Kunamandla amabili asebenza entweni, amandla okusunduza (F) kanye namandla okusunduza (F fric ). Amandla okusunduza anesiqondiso esifanayo nokusunduza kwento ngoba amandla okusunduza enza umsebenzi omuhle. Ngakolunye uhlangothi, amandla okusunduza anesiqondiso esiphambene nokusunduza kwento ukuze amandla okusunduza enze umsebenzi omubi.
Umsebenzi owenziwe ngamandla okusunduza:
W = F d = (350 Newton)(amamitha ayi-6) = 2100 Newton-meters = 2100 Joules
Umsebenzi owenziwe ngamandla okungqubuzana:
W = – (F fric )(s) = – (70 Newton)(6 amamitha) = – 420 Newton-amamitha = – 420 Joules
Inethiwekhi:
I-W inetha = amaJowule angu-2100 – amaJowule angu-420
I-W inethi = 1680 Joule
Impendulo efanele ithi C.
15. Into icindezelwa ngamandla avundlile angama-Newton angu-14 phansi okuqinile ngamandla okungqubuzana angama-Newton angu-10. Thola umsebenzi wenethi wokuhambisa into kuze kufike kumamitha angu-8.
A. 0.5 Joule
B. 3 Joule
C. 32 Joule
D. 192 Joule
Kwaziwa:
Amandla okusunduza (F) = 14 Newton
Amandla okungqubuzana (F fric ) = 10 Newtons
Ukufuduka kwento (d) = amamitha angu-8
Okufunwayo: Umsebenzi (W)
Isixazululo:
Kunamandla amabili asebenza entweni, amandla okusunduza (F) kanye namandla okungqubuzana (F fric ).
Amandla okusunduza anesiqondiso esifanayo nokusunduza kwento ukuze amandla okusunduza enze umsebenzi omuhle. Ngakolunye uhlangothi, amandla okusunduza anesiqondiso esiphambene nokusunduza kwento ukuze amandla okusunduza enze umsebenzi omubi.
Umsebenzi owenziwe ngamandla okusunduza:
W = F s = (14 Newton)(amamitha angu-8) = 112 Newton amamitha = 112 Joules
Umsebenzi owenziwe ngamandla okungqubuzana:
W = – (F fric )(s) = – (10 Newton)(amamitha angu-8) = – 80 Newton amamitha = – 80 Joules
Inethiwekhi:
I-W inetha = amaJowule angu-112 – amaJowule angu-80
I-W inethi = 32 Joule
Impendulo efanele ithi C.
16. Thola umsebenzi we-net ngokusekelwe kumfanekiso ongezansi.
A. 360 Joule
B. 450 Joule
C. 600 Joule
D. 750 Joule
Isixazululo:
Umsebenzi = Amandla (F) x ukufuduka (d)
Umsebenzi = Indawo kanxantathu 1 + indawo kanxantathu + indawo kanxantathu 2
Work = 1/2(40-0)(3-0) + (40-0)(9-3) + 1/2(40-0)(12-9)
Umsebenzi = 1/2(40)(3) + (40)(6) + 1/2(40)(3)
Umsebenzi = (20)(3) + 240 + (20)(3)
Umsebenzi = 60 + 240 + 60
Umsebenzi = ama-Joule angu-360
Impendulo eyiyo ngu-A.
17. Ucezu lokhuni olunobude obungu-60 cm luxhunywe phansi. Ukhuni lushaywa ngesando esingamakhilogremu angu-10 ukusuka ekuphakameni okungama-40 cm ngaphezu kwengaphezulu kokhuni. Uma amandla okumelana ajwayelekile omhlabathi engu-2 x 10 3 N futhi ukusheshisa ngenxa yamandla adonsela phansi kungu-10 m/s 2 , khona-ke ukhuni luzongena ngokuphelele emhlabathini ngemva kokushaya….
A. 4
B. 16
C. 28
D. 30
Kwaziwa:
Isisindo sesando (m) = 10 kg
Ukusheshisa ngenxa yamandla adonsela phansi (g) = 10 m/ s 2
Isisindo sesando (w) = mg = (10)(10) = 100 kg m/s 2
Ukususwa kwesando ngaphambi kokushaya ukhuni (d) = 40 cm = 0.4 amamitha
Ukumelana kokhuni (F) = 2 x 10 3 N = 2000 N
Ubude bokhuni = 60 cm = 0.6 amamitha
Okufunwayo: Ukhuni luzongena ngokuphelele emhlabathini ngemva… kokushaya.
Isixazululo:
Umsebenzi owenziwe ngesando lapho isando sihamba ibanga elingamamitha angu-0.4 uwukuthi:
W = F d = ws = (100 N)(0.4 m) = 40 Nm = 40 Joules
Umsebenzi owenziwe ngamandla okumelana nomhlabathi:
W = F d = (2000 N)(0.6 m) = 1200 Nm = 1200 Joules
Ukhuni luzongena ngokuphelele emhlabathini ngemva… kokushaya.
AmaJoules angu-1200 / amaJoules angu-40 = 30
Impendulo efanele ngu-D.
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