Imithetho kaNewton yokuhamba - izinkinga nezixazululo

Imithetho kaNewton yokuhamba - izinkinga nezixazululo

Umthetho wokuqala wokunyakaza kukaNewton

1. Uma kungekho mandla asebenzayo entweni, khona-ke:

(1) into ayisheshiswanga

(2) into ephumule

(3) ushintsho lwejubane lento = 0

(4) into ayikwazi ukuhamba ngesivinini esingaguquki

Yisiphi isitatimende esinembile?

Isixazululo

Isitatimende esifanele:

(1) Into ayisheshiswanga

Amandla e-net abangela ukusheshisa kwento. Ngakho-ke uma kungekho mandla e-net khona-ke izinto azisheshiswa.

(2) Into ephumule

Umthetho wokuqala kaNewton wokunyakaza uthi uma kungekho mandla asebenzayo entweni khona-ke into ihlala iphumule noma into ihlala ihamba ngesivinini esingaguquki.

(3) Ukushintsha kwejubane lento = 0

Ukushintsha kwejubane = ukusheshisa. Ukushintsha kwejubane kusho ukuthi akukho ukusheshisa. Uma kungekho ukusheshisa, akukho mandla asebenzayo entweni.

Into esesiliftini

2. Isisindo somuntu osesiliftini lapho ephumule = 500 N. Ukusheshisa ngenxa yamandla adonsela phansi kungu-10 m/s ² . Uma isilifti sisheshisa, amandla okucindezela angu-750 N. Kuyini ukusheshisa kwesilifti.

Kwaziwa:

Isisindo somuntu (w) = 500 Newton = 500 kg ms ^–2 (ukuphakamisa lapho uphumule)

Ukusheshisa kwamandla adonsela phansi (g) = 10 ms ^–2

Isisindo somuntu (m) = 500 / 10 = 50 kg

Amandla okucindezela (T) = 750 N (ukusheshisa ukuphakama)

Isisindo se-lifti asinakwa.

Kufunwa: Ukusheshisa ama-lifti

Isixazululo:

Ilifti lapho iphumule, akukho ukusheshisa (a = 0). Izenzo zamandla phezulu zinesibonakaliso sokuhlanganisa kanye nezenzo zamandla phansi zinesibonakaliso sokususa.

ΣF = ma

T – w = 0

T = w

T = 500 Newton

Uma ilifti ishesha yehla khona-ke amandla okucindezela amancane kakhulu angaba ngu-500 N. Ngaphandle kwalokho, uma ilifti ishesha yenyuka khona-ke amandla okucindezela makhulu angaba ngu-500 N.

Amandla okucindezela = 750 N ngoba ilifti ishesha iye phezulu. Izenzo zamandla phezulu zinesibonakaliso sokuhlanganisa kanye nezenzo zamandla phansi zinesibonakaliso sokususa.

T – w = ma

750 – 500 = 50 a

250 = 50 a

a = 250/50

a = 5.0 ms ^–2

3. Umuntu onesisindo esingu-60 kg eseliftini usheshise wehla ngesivinini esingu-3 m/s ^2. Uma ukusheshiswa ngenxa yamandla adonsela phansi kungu-10 m/s ² , yimaphi amandla avamile asetshenziswa phansi kwesilifti kumuntu.

Kwaziwa:

Isisindo (m) = 60 kg

Ukusheshisa komuntu kanye ne-lifti (a) = 3 m/s ²

Ukusheshisa ngenxa yamandla adonsela phansi (g) = 10 m/s ²

Isisindo (w) = mg = (60)(10) = 600 amaNewton

Okufunwayo: Amandla avamile (N)

Isixazululo:

Kunezenzo ezimbili zamandla kumuntu ose-lifti, okuyisisindo (w) somuntu kanye namandla ajwayelekile (N) asetshenziswa phansi kumuntu. Kunezinhlobo ezintathu ze-vector, okuyisisindo (w), amandla ajwayelekile (N) kanye nokusheshisa kwe-lifti, lapho isisindo sisebenza phansi, amandla avamile asebenza phezulu, ukusheshisa kwe-lifti kwehla. Inani le-vector elisebenza phansi linesibonakaliso sokuhlanganisa kanye nenani le-vector elisebenza phezulu linesibonakaliso sokususa.

∑F = ma

w – N = (60)(3)

600 – N = 180

N = 600 – 180

N = 420 Newton

4. Into enesisindo esingama-40 kg esiliftini isheshiswe iye phezulu. Uma phansi kwesilifti kune-520 N entweni futhi ukusheshiswa ngenxa yamandla adonsela phansi kungu-10 m/s ^2. Kuyini ukusheshiswa kwesilifti?

Kwaziwa:

Isisindo (m) = 40 kg

Amandla ajwayelekile (N) = 520 N

Ukusheshisa ngenxa yamandla adonsela phansi (g) = 10 m/s ²

isisindo (w) = mg = (40)(10) = 400 N

Kufunwa: Ukusheshisa ama-lifti

Isixazululo:

∑F = ma

400 – 520 = (40)(a)

-120 = (40)(a)

a = -120/40

a = -3 m/s ²

Ukusheshisa kwe-lifti kungu-3 m/s ^2. Uphawu lokususa lubonisa ukuthi i-lifti iya phezulu.

5. Into engamakhilogremu angu-60 esiliftini isheshise yehla ngesivinini esingu-3 m/s ^2. Yimaphi amandla asetshenziswa yizinto ezisephansi lesilifti.

Kwaziwa:

Isisindo (m) = 60 kg

Isisindo (w) = mg = (60 kg)(10 m/s ² ) = 600 kg m/s ² = 600 amaNewton

Ukusheshisa kwe-lifti (a) = 3 m/s ² , phansi

Okufunwayo: Amandla asetshenziswa yinto ephansi kwe-lifti.

Isixazululo:

Ilifti isheshiswe yehla ngesivinini esingu-3 m/s . Izenzo zokuphoqelela phansi zinesibonakaliso sokuhlanganisa kanye nezenzo zokuphoqelela phezulu zinesibonakaliso sokuncishiswa.

w – N = ma

N = w – ma

N = 600 – (60)(3)

N = 600 – 180

N = 420 Newton

Amandla asetshenziswa yinto esesitezi se-lifti = 420 N.

6. Amabhulokhi amabili axhunywe ngentambo egijima phezu kwe-pulley. Unganaki isisindo sentambo ne-pulley nanoma yikuphi ukungqubuzana ku-pulley. Isisindo sebhulokhi A singama-6 kg kanti isisindo sebhulokhi B singama-2 kg. Ukusheshisa ngenxa yamandla adonsela phansi angama-10 m/s ^2. Iyini amandla okucindezela?

Kwaziwa:

m _A = 6 kg, m _B = 2 kg, g = 10 m/s ²

w _A = m _A g = (6 kg)(10 m/s ² ) = 60 kg m/s ²

w _B = m _B g = (2 kg)(10 m/s ² ) = 20 kg m/s ²

Okufunwayo: amandla okucindezela (T)?

Isixazululo:

w _A > w _B ukuze u-m _A ehle phansi , u-m _B ehle phezulu.

Umthetho wesibili kaNewton:

Σ F = ma

w _A – w _B = (m _A + m _B ) a

60 – 20 = (6 + 2) a

40 = (8) a

a = 40 / 8 = 5 m/s ²

Amandla okucindezela:

m _A wehlela phansi:

w _A – T _A = m _A a

60 – T _A = (6)(5)

60 – TA ₌ 30

TA = 60 – ₃₀

I-T ₂ = 30 Newton

m _B inyukela phezulu:

T _B – w _B = m _B a

I-T _B – 20 = (2)(5)

I-T _B – 20 = 10

I-T _B = 10 + 20

I-T ₁ = 30 Newton

Amandla okucindezela (T) = amaNewton angu-30.

7. Isisindo sento A = 5 kg, ukusheshisa ngenxa yamandla adonsela phansi (g) = 10 ms ^-2 . Into A yehla ngo-2.5 ​​ms ^-2 . Iyini isisindo sika-B?

Kwaziwa:

Isisindo A (m _A ) = 5 kg

Ukusheshisa ngenxa yamandla adonsela phansi (g) = 10 m/s ²

Ukusheshisa kwento A (a) = 2.5 m/s ²

Isisindo A (w _A ) = (m _A )(g) = (5)(10) = 50 AmaNewton

Okufunwayo: Isisindo sento B (m _B )

Isixazululo:

Ibhulokhi A liyehla ukuze isisindo sento A (w _A ) sikhulu kunesisindo sento B (w _B ).

Sebenzisa umthetho wesibili kaNewton:

Σ F = ma

w _A – w _B = (m _A + m _B ) a

50 – (m _B )(10) = (5 + m _B ) (2.5)

50 – 10 m _B = 12.5 + 2.5 m _B

50 – 12.5 = 2.5 m _B + 10 m _B

37.5 = 12.5 m _B

m _B = 3 kg

8. Ukusheshisa ngenxa yamandla adonsela phansi kungu-10 m/s ^2. Iyini amandla okucindezela.

Kwaziwa:

Isisindo sento 1 (m₁) = 2 kg

Isisindo sento 2 (m ₂ ) = 3 kg

Ukusheshisa ngenxa yamandla adonsela phansi (g) = 10 m/s ²

Isisindo 1 (w ₁ ) = (m ₁ )(g) = (2 kg)(10 m/s ² ) = 20 kg m/s ²

Isisindo 2 (w ₂ ) = (m ₂ )(g) = (3 kg)(10 m/s ² ) = 30 kg m/s ²

Kufunwa: amandla okucindezela (T)

Isixazululo:

w ₂ > w ₁ ukuze u-m ₂ ahambe phansi kanti u-m ₁ ahambe phezulu.

Umthetho wesibili kaNewton wokunyakaza:

Σ F = ma

w ₂ – w ₁ = (m ₁ + m ₂ ) a

30 – 20 = (2 + 3) a

10 = (5) a

a = 10 / 5 = 2 m/s ².

Amandla okucindezeleka?

m2 _iqhubekela phansi

w ₂ – T ₂ = m ₂ a

30 – T ₂ = (3)(2)

30 – T ₂ = 6

Isigaba ₂ = 30 – 6

I-T ₂ = 24 Newton

m ₁ iqhubekela phezulu

I-T ₁ – w ₁ = m ₁ a

I-T ₁ – 20 = (2)(2)

Isigaba ₁ – 20 = 4

I-T ₁ = 20 + 4

I-T ₁ = 24 Newton

Amandla okucindezela (T) = amaNewton angu-24.

1. Umbuzo: Kungani umthetho wokuqala kaNewton wokunyakaza ugcizelela ukubaluleka kwamandla angaphandle ekushintsheni isimo sokunyakaza kwento? Impendulo: Umthetho wokuqala kaNewton wokunyakaza, ovame ukubizwa ngokuthi umthetho we-inertia, uthi into izohlala iphumule noma inyakaze ngendlela efanayo emgqeni oqondile ngaphandle kokuthi isetshenziswe amandla angaphandle. Lo mthetho ugcizelela ukuthi amandla angaphandle, hhayi izimfanelo zangaphakathi zento ngokwayo, angashintsha isimo sayo sokunyakaza.
2. Umbuzo: Umthetho wesibili kaNewton uhlobana kanjani amandla, ubukhulu, kanye nokusheshisa? Impendulo: Umthetho wesibili kaNewton wokunyakaza uthi amandla asebenza entweni alingana nobunzima baleyo nto obuphindaphindwa ngokusheshisa kwayo ($F=ma$Lokhu kusungula ukulingana okuqondile phakathi kwamandla nokusheshisa kanye nokulingana okuphambene phakathi kobukhulu nokusheshisa, uma kunikezwa amandla angaguquki.
3. Umbuzo: Kungani ungawuzwa uMhlaba uhamba yize uhlala ushukuma? Impendulo: Lokhu kuwumfanekiso womthetho wokuqala kaNewton. Thina, kanye noMhlaba nakho konke okukuwo, sihamba ndawonye ngokulinganayo. Ngaphandle kwamandla angaphandle okushintsha lesi simo sokunyakaza, akukho muzwa wokusheshisa noma wokushintsha, okwenza kubonakale sengathi simile.
4. Umbuzo: Umthetho wesithathu kaNewton uchaza kanjani isenzo serokhethi esikhaleni? Impendulo: Umthetho wesithathu kaNewton uthi kuyo yonke into eyenzekayo, kukhona ukusabela okulinganayo nokuphambene. Irokhethi esikhaleni liyaziqhuba ngokuxosha amagesi okukhipha umoya emuva. Isenzo yigesi ehamba emuva, kanti ukusabela yirokhethi ehamba phambili.
5. Umbuzo: Kungani uqhubeka ngemoto uma ima ngokuzumayo? Impendulo: Ngokomthetho wokuqala kaNewton, umzimba wakho uyaqhubeka nesimo sawo sokunyakaza (phambili) lapho imoto ima. Ngaphandle kokuba amandla (njengebhande lesihlalo) asebenze kuwe, uzoqhubeka uqhubekela phambili ngenxa yokungabi namandla.
6. Umbuzo: Uma uphaphe nesando kuphonswa endaweni engenamuntu, imithetho kaNewton ingabikezela ini ngokunyakaza kwazo? Impendulo: Endaweni engenamoya, akukho ukumelana nomoya. Ngokusekelwe emithethweni yokuqala neyesibili kaNewton, kokubili uphaphe kanye nesando kufanele kuwele ngesivinini esifanayo futhi kushaye phansi ngesikhathi esisodwa ngoba amandla odwa asebenza kuzo amandla adonsela phansi.
7. Umbuzo: I-airbag iwanciphisa kanjani amathuba okulimala ngesikhathi sengozi yemoto? Impendulo: Umthetho wokuqala kaNewton ubonisa ukuthi into ehambayo ihlala inyakaza. Lapho kuphahlazeka, ukunyakaza komuntu phambili kuyaqhubeka. Isikhwama somoya sinikeza indawo ethambile ekhulisa isikhathi sokunciphisa ijubane, ngaleyo ndlela kunciphisa amandla atholwa ngumuntu ngokusho $F=ma$.
8. Umbuzo: Kungani kulula ukusunduza inqola yokuthenga engenalutho kuneyokulayisha? Impendulo: Umthetho wesibili kaNewton ($F=ma$) kusikisela ukuthi ngenani elifanayo lamandla asetshenziswayo, into enobunzima obuncane (inqola engenalutho) izoba nokusheshisa okukhulu kunento enobunzima obukhulu (inqola elayishiwe).
9. Umbuzo: Kungani umuntu obhukudayo esunduza amanzi emuva ukuze aqhubekele phambili? Impendulo: Lokhu kuwukubonakaliswa komthetho wesithathu kaNewton. Lapho umbhukudi esunduza amanzi emuva (isenzo), kuba nokusabela okulinganayo nokuphambene okuqhubezela umbhukudi phambili.
10. Umbuzo: Ukungqubuzana kuhlobana kanjani nomthetho wokuqala kaNewton? Impendulo: Ukungqubuzana kungamandla angaphandle angasebenza ezintweni ukuze azinciphise noma amise ukunyakaza kwazo. Ngaphandle kokungqubuzana (noma amanye amandla angaphandle), into ingaqhubeka nesimo sayo sokunyakaza unomphela njengoba kushiwo umthetho wokuqala kaNewton.