1. Ibhokisi elingamakhilogremu angu-2 liyehla ngesivinini kusuka ku-10 m/s liye ekuphumuleni. I-coefficient ye -kinetic friction ingu-0.2. Ukusheshisa ngenxa yamandla adonsela phansi kungu-10 m/s 2. Ubukhulu bokufuduka buyini?
Kwaziwa;
Isisindo (m) = 2 kg
Ijubane lokuqala (v o ) = 10 m/s
Ijubane lokugcina (v t ) = 0 m/s
I-coefficient ye-kinetic friction ( μk ) = 0.2
Isisindo (w) = mg = (1 kg)(10 m/s 2 ) = 10 kg m/s 2 = 10 N
Okufunwayo: Ubukhulu bokufuduka (d)
Isixazululo:
Umgomo wamandla okusebenza nowokusebenza :
W nc = ΔEM
W nc = ΔEK + ΔEP
I-W nc = ½ m (v t 2 – vo 2 ) + mgh
W nc = umsebenzi owenziwe ngamandla angewona awokugcina imithetho asebenza entweni
ΔEK = ushintsho lwamandla e-kinetic
ΔEP = ushintsho emandleni angase abe khona
m = isisindo
v = ijubane
g = ukusheshisa ngenxa yamandla adonsela phansi
h = ushintsho ekuphakameni
Ushintsho ekuphakameni h = 0 ngakho-ke ΔEP = 0
W nc = ΔEK
Umsebenzi owenziwe ngamandla angewona awokugcina imithetho:
W nc = -F c d = – μ k N d = – μ k wd = – μ k mgd
I-W nc = -(0.2)(2)(10)(s)
W nc = – (4)(2)
Uphawu lokususa lubonisa ukuthi isiqondiso samandla okungqubuzana kwe-kinetic siphambene nesiqondiso sokufuduka.
Ushintsho kumandla e-kinetic:
ΔEK = ½ m (v t 2 – v o 2 ) = ½ (2)(0 – 10 2 ) = 0 – 100 = -100
Ubukhulu bokufuduka:
W nc = ΔEK
– 4 s = – 100
s = -100/-4
s = 25 m
[irp]
2. Ibhlokhi liyashelela phansi endizeni ethambekele. I-coefficient ye-kinetic friction ingu-0.4. Ukusheshisa ngenxa yamandla adonsela phansi kungu -g = 10 ms -2 . Thola ijubane lokugcina lapho ibhlokhi lishaya phansi.
Kwaziwa:
Ukuphakama kokuqala (h₂o₂ ) = 6 m
Ukuphakama kokugcina (h t ) = 0 m
Ijubane lokuqala (v o ) = 0
I-coefficient ye-kinetic friction ( μk ) = 0.4
Ukusheshisa ngenxa yamandla adonsela phansi (g) = 10 ms -2
cos θ = 8/10
Ingxenye eqondile yesisindo = w y = w cos θ = mg cos θ = m (10) (8/10) = m (10)(4/5) = m (40/5) = 8 m
Amandla ajwayelekile = N = w y = 8 m
Amandla okungqubuzana kwe-kinetic = f k = μ k N = μ k w y = (0.4)(8 m) = 3.2 m
Okufunwayo: Ijubane lokugcina (v t )
Isixazululo:
Umgomo wamandla okusebenza nowokusebenza:
W nc = Δ EM
W nc = Δ EK + Δ EP
Ushintsho kumandla e-kinetic:
ΔEK = 1/2 m (vt2 - vo2) = 1/2 m (vt2 - 0) = 1/2 mvt2
Ushintsho emandleni angaba khona:
Δ EP = mg (h t – ho ) = m (10)(0-6) = m (10)(-6) = – 60 m
Umsebenzi owenziwe ngamandla okungqubuzana kwe-kinetic:
Ukuphakama nc = – f ks = – ( 3.2 m)(10) = – 32 m
Uphawu lokususa lubonisa ukuthi isiqondiso samandla okungqubuzana kwe-kinetic siphambene nesiqondiso sokufuduka.
Ijubane lokugcina (v t ):
W nc = Δ EK + Δ EP
– 32 m = 1/2 mv t 2 – 60 m
– 32 m = m (1/2 v t 2 – 60)
– 32 = 1/2 v t 2 – 60
– 32 + 60 = 1/2 v t 2
28 = 1/2 v t 2
2 (28) = v t 2
56 = v t 2
v t = √4.14
v t = 2 √14 ms -1
[irp]
3. Ibhulokhi liwela phansi endizeni ethambekele phansi. Ijubane lokuqala lingu-0 m/s kanti ijubane lokugcina lingu- 10 ms -1 . Uma amandla okungqubuzana kwe-kinetic engu-2 N kanye nokusheshisa ngenxa yamandla adonsela phansi u-g = 10 ms -2 , kuyini ukuphakama (h)?
Kwaziwa:
Isisindo (m) = 1 kg
Ijubane lokuqala (v o ) = 0 (ukuphumula kwebhulokhi)
Ijubane lokugcina (v t ) = 10 ms -1
Ukuphakama kokuqala (h o ) = h
Ukuphakama kokugcina (h t ) = 0
Amandla okungqubuzana kwe-kinetic (f k ) = 2 N
Ukusheshisa ngenxa yamandla adonsela phansi (g) = 10 ms -2
Okufunwayo: Ukuphakama (h)
Isixazululo:
Umsebenzi owenziwe ngamandla okungqubuzana kwe-kinetic:
W nc = – f ks = – (2 )(15) = – 30
Uphawu lokususa lubonisa ukuthi isiqondiso samandla okungqubuzana kwe-kinetic siphambene nesiqondiso sokufuduka.
Ushintsho kumandla e-kinetic:
ΔEK = 1/2 m (vt2 - vo2) = 1/2 (1)(102 - 0) = 1/2 (102) = 1/2 (100= = 50
Ushintsho emandleni angaba khona:
Δ EP = mg (h t – ho ) = (1)(10)(0-h) = (10)(-h) = -10 h
Umgomo wamandla okusebenza nowokusebenza:
W nc = Δ EK + Δ EP
– 30 = 50 – 10 amahora
Amahora ayi-10 = 50 + 30
Amahora ayi-10 = 80
h = 80/10
h = 8 m
4Uma ibhlogo lihamba phansi endaweni ethambekele kakhulu, khona-ke….
A. Umsebenzi owenziwa ngamandla adonsela phansi ebhulokini mkhulu kunoshintsho lwamandla angaba khona ebhulokini.
B. Amandla omshini ayanda
C. Inani lamandla e-kinetic kanye namandla akhona ancishisiwe
D. Umsebenzi wenziwa ngamandla okungqubuzana alingana noshintsho lwamandla e-kinetic ebhulokhi
Isixazululo
U-A unephutha
Umsebenzi owenziwa ngamandla adonsela phansi ebhulokini ulingana noshintsho emandleni adonsela phansi ebhulokini.
U-B unephutha
Uma indiza efakwe ngaphakathi ibushelelezi khona-ke amandla omshini webhloko ahlala njalo. Uma iphezulu kwendiza ethambekele futhi ingakahambi, amandla omshini webhloko alingana namandla okudonsa amandla adonsela phansi. Ibhloko lisaphumule ngakho amandla alo e-kinetic ayi-zero. Uma lihamba phansi kwendiza ethambekele, ukuphakama kwebhloko kuyancishiswa ngakho amandla okudonsa amandla adonsela phansi nawo ayancishiswa. Amandla okudonsa amandla adonsela phansi ayancipha ngoba ashintsha abe amandla e-kinetic. Nakuba amandla okudonsa amandla aguquka abe amandla e-kinetic, amandla omshini ahlala njalo.
Uma indiza ethambekele ilukhuni khona-ke amandla omshini ebhulokhi ayancipha ngenxa yomsebenzi ongemuhle owenziwa amandla omshini. Amandla omshini angamandla angalondolozi. Umsebenzi owenziwa amandla angalondolozi entweni ubangela ukuba amandla omshini ento anciphe.
U-C ulungile
Indiza ethambekele ilukhuni ngakho-ke kukhona amandla okungqubuzana aphonsela inselelo ukunyakaza kwebhlokhi. Amandla okungqubuzana angamandla angaguquki. Amandla okusebenza-omshini we-theorem athi umsebenzi owenziwa amandla angaguquki (isibonelo amandla okungqubuzana) ulingana noshintsho lwamandla omshini. Kulokhu kuphishekela, amandla omshini ayancipha.
Amandla omshini ebhulokhi = amandla adonsela phansi + amandla e-kinetic.
U-D unephutha.
Umsebenzi owenziwa amandla okungqubuzana ebhulokini ulingana noshintsho lwamandla omshini webhulokhi, hhayi ushintsho lwamandla okungqubuzana ebhulokhi. Kuyiqiniso ukuthi amandla okungqubuzana aphonsela inselelo ukunyakaza kwebhulokhi ngakho-ke anciphisa ijubane lebhulokhi futhi anciphise amandla okungqubuzana ebhulokhi. Kodwa qaphela ukuthi amandla okungqubuzana ebhulokhi avela emandleni anamandla adonsela phansi. Ngakho-ke kuyiqiniso ukuthi umsebenzi wenziwa amandla okungqubuzana alingana noshintsho lwamandla omshini (amandla omshini ayancipha).
Impendulo efanele ithi C.
5. Into ephansi eliqinile iyashaywa ukuze inyakaze imizuzwana emi-3 bese iyama. Uma isisindo esaziwayo sale nto singamagremu ayi-10, amandla okungqubuzana phakathi kwento nephansi angamakhiloyne ama-2. Thola umsebenzi owenziwe amandla okungqubuzana.
A. 0.18 J
B. -0.18 J
C. 0.36 J
D. -0.36 J
Kwaziwa:
Isikhawu sesikhathi (t) = imizuzwana eyi-3
Isivinini sokugcina (v t ) = 0 m/s (ukuphumula kwezinto)
Isisindo sento (m) = 10 amagremu = 10/1000 kg = 1/100 kg = 0.01 kg
I-Friction force (F) = 2 kilodynes = 2 x 10 3 ama -dynes
Okufunwayo: Umsebenzi (W) owenziwe ngamandla okungqubuzana
Isixazululo:
Ukuguqulwa kwamayunithi amandla:
1 Newton = 1 x 10 5 dyne
I-dyne eyi-1 = 1 / 10 5 AmaNewton = 1 x 10 -5 AmaNewton = 10 -5 AmaNewton
Amandla okungqubuzana (F) = 2 x 10 3 dyne = 2 x 10 3 x 10 -5 Newton = 2 x 10 -2 Newton = 2/100 Newton = 0.02 Newton
I-Theorem work-mechanical energy ithi umsebenzi wenziwa ngamandla angewona awokugcina entweni elingana noshintsho emandleni okusebenza ento.
Uma into ihamba endizeni ethambekele khona-ke amandla omshini (ME) = amandla adonsela phansi (PE) + amandla omshini (KE). Kodwa uma into ihamba endizeni evundlile ukuze kungabikho ushintsho ekuphakameni, amandla omshini = amandla omshini. Endizeni evundlile, amandla adonsela phansi ayi-zero ngoba akukho ushintsho ekuphakameni.
Amandla okungqubuzana angamandla angaguquki. Amandla okungqubuzana avame ukunciphisa ijubane lento kanye namandla okuhambahamba kwento. Angaphetha ngokuthi umsebenzi owenziwa amandla okungqubuzana entweni ulingana nokwehla kwamandla omshini.
Ngokwezibalo:
Umsebenzi (W) = Ushintsho lwamandla omshini (ΔEM)
F s = ΔEP + ΔEK
F s = mg Δh + ½ m (v t 2 – vo 2 )
F s = mg (0) + ½ m (0 2 – vo 2 )
Fs = 0 + ½ m (– (v o 2 ))
F s = – ½ mv o 2 ———— Isibalo 1
Incazelo: F = amandla okungqubuzana, d = ukufuduka, m = isisindo, v o = isivinini sokuqala
Ukufuduka (d) kanye nesivinini sokuqala (vo o ) akukaziwa okwamanje ngoba kuqala bala u-v o noma u-d. Umsebenzi owenziwe ngamandla okungqubuzana ubalwe kusetshenziswa esinye sezibalo ngemuva kuka-v o noma u-d owaziwayo.
Isibalo sokufuduka (d) ekuhambeni okuqondile okungalingani:
v t 2 = vo 2 + 2 (-a) s
Isivinini sokugcina (v t ) = 0 kanye nokusheshisa (a) kusayinwe ngokuthi kuphambene ngoba into yehlisiwe (isivinini sento sinciphile).
0 = vo2 – izikhangiso ezi-2
vo2 = isikhangiso esingu-2
d = v o 2/2 a———— Isibalo 2
Shintsha u-d ku-equation 2 no-d ku-equation 1:
F d = – ½ mv o 2
F (v o 2 /2a) = – ½ mv o 2
(F/2a) v o 2 = – ½ mv o 2
F/2a = – ½ m
F = (2)(a)(-1/2)(m)
F = – (a)(m)
a = – (F / m)
a = – 0.02 Newtons / 0.01 kg
a = – 2 Newton/kg
a = – 2 m/s 2
Isibalo sokubala isivinini sokuqala (v o ) ekuhambeni okuqondile okungalingani:
v t = vo o + at —–> Isivinini sokugcina (v t ) = 0, Ukusheshisa (a) = 2 m/s 2 , isikhawu sesikhathi (t) = imizuzwana emi-3
0 = vo + (-2)(3)
0 = v o – 6
v o = amamitha ayi-6/umzuzwana
Umsebenzi (W) owenziwe ngamandla okungqubuzana:
W = – ½ mv o 2 = -1/2 (0.01)(6 2 ) = -1/2 (0.01)(36)
W = -1/2 (0.36)
W = – 0.18 Joule
Umsebenzi owenziwe amandla okungqubuzana usayinwe ungemuhle okusho ukuthi umsebenzi wehlisa amandla okusebenza ento.
Uma kwaziwa ukuthi u-d umsebenzi ungabalwa kusetshenziswa i-equation ka- W = F d.
Impendulo efanele ngu-B.
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- Umsebenzi owenziwa ngezinkinga zamandla nezixazululo
- Izinkinga zamandla e-kinetic kanye nezixazululo zomsebenzi
- Izinkinga nezixazululo zesimiso samandla okusebenza-okusebenza ngomshini
- Izinkinga zamandla adonsela phansi kanye nezixazululo ezingaba khona
- Amandla angaba khona ezinkinga zentwasahlobo ezinwebekayo nezixazululo
- Izinkinga zikagesi nezixazululo
- Ukusetshenziswa kokulondolozwa kwamandla omshini ukuze kuqhutshekwe nokuwa kwamahhala
- Ukusetshenziswa kokulondolozwa kwamandla omshini wokunyakaza okuphezulu nokwehla ekunyakazeni kokuwa kwamahhala
- Ukusetshenziswa kokulondolozwa kwamandla okusebenza ukuze kushukunyiswe endaweni egobile
- Ukusetshenziswa kokulondolozwa kwamandla omshini ukuze kushukunyiswe endizeni ethambekele
- Ukusetshenziswa kokulondolozwa kwamandla okusebenza ngomshini wokunyakaza okubonakalayo
