Mehlala ea lipotso mabapi le mosebetsi le matla

Mehlala e 16 ea Lipotso tsa Mosebetsi le Matla

Theorem Matla a Kinetic a Mosebetsi

1. Matla a sa fetoheng a 60 N a sebetsa metsotsoana e 12 nthong e boima ba 10 kg. Ntho eo

e na le lebelo la pele la 6 m/sc ka lehlakoreng le le leng le matla.

(1) Mosebetsi o entsoeng nthong eo ke li-joule tse 30.240

(2) Matla a ho qetela a kinetic a ntho ke 30.240 joules.

(3) Matla a hlahisoang ke li-watts tse 2.520

(4) Keketseho ea matla a kinetic a ntho ke li-joule tse 180.

Polelo e nepahetseng ke…

A. 1, 2 le 3

B. 1 le 3

C. 1 le 4

D. 4 feela

E. tsohle li nepahetse

Puisano

Hoa tsebahala hore:

Matla (F) = 60 N

Nako ea ho arohana (t) = metsotsoana e 12

Boima ba ntho (m) = 10 kg

Lebelo la pele (vo _o ) = 6 m/s

O botsitse: Ke polelo efe e nepahetseng?

Karabo:

Ho potlakisa ntho:

∑ F = ma

60 = 10 a

a = 60 / 10 = 6 m/s ²

Lebelo la ho qetela:

v_t = v_o + ho

v_t = 6 + (6)(12)

v _t = 6 + 72

v _t = 78 m/s

Sebaka se tsamailoeng ka metsotsoana e 12:

s = vo _o t + 1/2 ho ²

s = (6)(12) + 1/2 (6)(12) ²

s = 72 + (3)(144)

s = 72 + 432

s = limithara tse 504

(1) Mosebetsi o phethiloe

W = F s = (60)(504) = 30.240 Joule

(2) Matla a ho qetela a kinetic a ntho

EK = 1/2 mv_t² = 1/2 (10)(78)² = (5)(6084) = 30.420 Li-joule

(3) Matla a hlahisoang

P = W / t = 30.240 / 12 = 2.520 Joules/motsotsoana

(4) Keketseho ea matla a kinetic

ΔEK = 1/2 mv_t² – 1/2 mv_o² = 1/2 m (v_t² - v_o²) = 1/2 (10)(78² - 6²) = 5 (6084 –36) = 5 (6048)

ΔEK = 30.240 Joule

Karabo e nepahetseng ke B.

2. Lintlha tse mabapi le phetoho ea lebelo la ntho e tsamaeang moleng o otlolohileng li hlahisoa ka tsela e latelang. Mosebetsi o moholo ka ho fetisisa o etsoa ke palo ea ntho….

A. 1

B. 2

C. 3

D. 4

E. 5

Puisano

Khopolo-taba ea matla a kinetic a mosebetsi:

Mosebetsi oohle = phetoho ea matla a kinetic

W_kakaretso = ½ m (v_t² - v_o²)

Likhoebo tse kholo ka ho fetisisa ke:

W ₁ = ½ (8)(4 ² – 2 ² ) = (4)(16 – 4) = (4)(12) = 48 Dijoule

W ₂ = ½ (8)(5 ² –3 ² ) = (4)(25 – 9) = (4)(16) = 64 Joule

W ₃ = ½ (10)(6 ² – 5 ² ) = (5)(36 – 25) = (5)(11) = 55 Dijoule

W ₄ = ½ (10)(4 ² – 0 ² ) = (5)(16 – 0) = (5)(16) = 80 Dijoule

W ₅ = ½ (20)(3 ² – 3 ² ) = (10)(9 – 9) = (10)(0) = 0 Dijoule

Karabo e nepahetseng ke D.

3. Odi o kganna koloi ya boima ba 4000 kg tseleng e otlolohileng ka lebelo la 25 m/s. Ha a bona sephethephethe se le hole, o ile a brake, a fokotsa lebelo la koloi butle-butle ho fihla ho 15 m/s. Mosebetsi o etswang ke lebotho la ho brake ke….

A. 200 kJ

B. 300 kJ

C. 400 kJ

D. 700 kJ

E. 800 kJ

Puisano

Hoa tsebahala hore :

Boima ba koloi (m) = 4000 kg

Lebelo la pele la koloi (v)_o) = 25 m/s

Lebelo la ho qetela la koloi (v_t) = 15 m/s

E botsitsoe : Na o sebetsa (W) koloing?

Karabo :

Khopolo-taba ea matla a kinetic a mosebetsi:

W_kakaretso = ½ m (v_t² - v_o²) = ½(4000)(15²-25²) = (2000)(225-625) = (2000)(-400) = -800.000 Dijoule = -800 kilojoule.

Karabo e nepahetseng ke E.

4. Bolo e boima ba 0,1 kg e lahlelwa ka ho rapama ka lebelo la 6 m/s ho tloha marulelong a moaho o bophahamo ba 5 m. Haeba lebelo le bakwang ke matla a khoheli sebakeng seo e le 10 m/s², joale matla a kinetic a bolo bophahamong ba 2 m ke….

A. 6,8 J

B. 4,8 J

C. 3,8 J

D. 3 J

E. 2 J

Puisano

Hoa tsebahala hore :

Boima (m) = 0,1 kg

Phetoho ea bolelele (h) = 5 m - 2 m = 3 metres

Ho potlaka ka lebaka la matla a khoheli (g) = 10 m/s ²

E botsitsoe : matla a kinetic (EK) bophahamong ba limithara tse 2?

Karabo :

Tsela eo bolo e tsamayang ka yona e bontshitswe setshwantshong se ka tlase.

Motsamao oa parabola joalokaha o bontšitsoe setšoantšong se kaholimo ke motsoako oa metsamao e 'meli e ka hlahlojoang ka thoko, moo motsamao o shebileng ka lehlakoreng le otlolohileng o leng ka mokhoa oa motsamao o ts'oanang o otlolohileng le motsamao ka lehlakoreng le otlolohileng ka sebopeho sa motsamao oa ho oa o lokolohileng.

Bothata bona bo rarolloa ho sebelisoa molao oa paballo ea matla a mechini, ka hona re nahana feela ka motsamao o otlolohileng ka mokhoa oa motsamao oa ho oa o lokolohileng.

Ntho e 'ngoe le e 'ngoe e oelang ka bolokolohi ha e na lebelo la pele (v)_o = 0) e le hore matla a pele a kinetic a ntho e be lefela (EK = ½ mv² = 0). Ka lehlakoreng le leng, ntho e qala ho tsamaya ho tloha bophahamong ba limithara tse 5 ka hodima lefatshe e le hore ntho e be le matla a kgoheli. Kahoo matla a pele a mechini a bolo ke matla a kgoheli. Ha bolo e qala ho theoha, matla a kgoheli a bolo a fetoha ho ba matla a kinetic. Matla a kgoheli a fetohang ho ba matla a kinetic ha bolo e tsamaya ho tloha bophahamong ba limithara tse 5 ka hodima lefatshe ho ya bophahamong ba limithara tse 2 ka hodima lefatshe ke: EP = mgh = (0,1)(10)(3) = 3 Joules. Ha bolo e le bophahamong ba limithara tse 2 ka hodima lefatshe, matla a kinetic a bolo ke 3 Joules.

Karabo e nepahetseng ke D.

5. Koloi e boima ba tonne e le 'ngoe e qala ho tloha moo e phomotseng. Ka mora motsotsoana lebelo la yona ke 5 m/s.^-1. Mosebetsi o etsoang ke enjene ea koloi ke…

A. 1000 Joule

B. 2.500 Joule

C. 5.000 Joule

D. 12.500 Joule

E. 25.000 Joule

Puisano

Hoa tsebahala hore :

Boima (m) = 1 ton = 1000 kg

Lebelo la pele (v)_o) = 0 (koloi e tsamaya ho tloha boemong bo sa sisinyeheng)

Lebelo la ho qetela (v)_t) = 5 m/s

E botsitsoe : Mosebetsi (W) o etsoang ke enjene ea koloi ke ofe?

Karabo :

Khopolo-taba ea matla a kinetic a mosebetsi:

W_kakaretso = ½ m (v_t² - v_o²)

Mosebetsi o etsoang ke enjene ea koloi ke:

W_kakaretso = ½ (1000)(5² - 0²) = (500)(25 – 0) = (500)(25) = 12.500 Joule

Karabo e nepahetseng ke D.

6. Bolo e boima ba digrama tse 500 e lahlelwa hodimo ho tloha fatshe ka lebelo la pele la 10 m/s.^-2Haeba g = 10 ms^-2, ebe mosebetsi o etsoang ke matla a khoheli a bolo ha e fihla bophahamong ba eona bo phahameng ke...

A. 2,5 J

B. 5,0 J

C. 25 J

D. 50 J

E. 500 J

Puisano

Hlokomoloha khanyetso ea moea.

Hoa tsebahala hore :

Boima ba bolo (m) = digrama tse 500 = 0,5 kg

Lebelo la pele (v)_o) = 10 m/s²

Lebelo la ho qetela (v)_t) = 0. Ha e le bophahamong bo phahameng ka ho fetisisa, ntho e ntse e le teng motsotsoana pele e kgutlisa tsela morao.

Ho potlaka ka lebaka la matla a khoheli (g) = 10 m/s ²

E botsitsoe : Mosebetsi (W) o etsoang ka boima ba bolo

Karabo :

Khopolo-taba ea matla a kinetic a mosebetsi :

Teori ea matla a sebetsang le kinetic e bolela hore mosebetsi oohle kapa boiteko bo etsoang ke matla a hlahang nthong bo lekana le phetoho ea matla a kinetic a ntho. Foromo ea theori ea matla a sebetsang le kinetic ke:

W_kakaretso = ΔEK = EK_t – EK_o

W_kakaretso = ½ mv_t² – ½ mv_o² = ½ m (v_t² - v_o²)

Lintlha :

EK_t = matla a ho qetela a kinetic, EK_o = matla a kinetic a pele, m = boima ba ntho, v_t = lebelo la ho qetela la ntho, v_o = lebelo la pele la ntho.

Boiteko bo felletseng :

Mosebetsi o etsoang ka boima ba bolo ho tloha nakong eo bolo e lahleloang ho fihlela bolo e fihla bophahamong ba eona bo phahameng ke:

W_kakaretso = ½ m (v_t² - v_o²) = ½ (0,5)(0² - 10²)

W_kakaretso = (0,25)(-100) = -25 Lijoule

Letšoao le fosahetseng le bontša hore tataiso ea ho falla ha bolo e fapane le tataiso ea matla a khoheli a bolo. Tsela ea ho falla ha bolo e ea holimo, ha tataiso ea matla a khoheli a bolo e le tlase. Matla a khoheli a etsa mosebetsi o fosahetseng holim'a bolo, ho bolelang hore mosebetsi o etsoang ke matla a khoheli o eketsa matla a khoheli a bolo 'me o fokotsa matla a eona a kinetic. Matla a khoheli a etsa mosebetsi o motle haeba tataiso ea matla a khoheli a bolo e tšoana le tataiso ea ho falla ha bolo (bolo e theohela tlase).

Karabo e nepahetseng ke C.

7. Bolo e boima ba 1 kg e lahleloa ntle le lebelo la pele ho tloha holimo ho moaho ho pholletsa le fensetere A mokatong o ka holimo ho ea fensetereng ea B mokatong o ka tlase ka phapang ea bophahamo ba 2,5 m (g = 10 ms).^-2). Ho hlokahala boiteko bo bokae ho tsamaisa bolo ho tloha fensetereng ya A ho ya fensetereng ya B?

A. 5 Joule

B. 15 Joule

C. 20 Joule

D. 25 Joule

E. 50 Joule

Puisano

Hoa tsebahala hore :

Boima ba bolo (m) = 1 kg

Lebelo la pele (vo _o ) = 0 m/s

Bophahamo (h) = limithara tse 2,5

Ho potlaka ka lebaka la matla a khoheli (g) = 10 m/s ²

E botsitsoe : Mosebetsi oohle nakong ea motsamao oa bolo

Karabo :

Lebelo la ho qetela la bolo (v_t)

Bolo e oa ntle le lebelo la pele, kahoo motsamao oa eona o nkoa e le ho oa ka bolokolohi. Taba ea pele, bala lebelo la ho qetela la bolo u sebelisa foromo ea ho oa ka bolokolohi. Ho potlaka ka lebaka la matla a khoheli (g) ke 10 m/s.², phetoho bophahamong ba bolo (h) = limithara tse 2,5 mme lebelo la ho qetela (v) le botsoa_t) ka hona sebelisa mokhoa v_t² = 2 gh

v_t² = 2 gh = 2(10)(2,5) = 2(25)

v_t = √2(25) = 5√2

Kahoo lebelo la ho qetela la bolo ke 5√2 m/s

Mosebetsi oohle = phetoho ea matla a kinetic

W_kakaretso = ΔEK = ½ m (v_t² - v_o²) = ½ (1){(5√2)² - 0²}

W_kakaretso = ½ (25)(2) = 25 Joule

Karabo e nepahetseng ke D.

8. Ntho e boima ba 2 kg qalong e tsamaya ka lebelo la 72 km/h.^-1Kamora ho tsamaya ka lebelo la 400 m, lebelo la ntho le ba 144 km/h.^-1 le (g = 10 ms^-2). Mosebetsi oohle o entsoeng ke ntho eo ka nako eo ke…

A. 20 J

B. 60 J

C. 1.200 J

D. 2.000 J

E. 2.400 J

Puisano

Hoa tsebahala hore :

Boima ba ntho (m) = 2 kg

Lebelo la pele (v)_o) = 72 km/h = 20 m/s

Lebelo la ho qetela (v)_t) = 144 km/h = 40 m/s

Sebaka se tsamailoeng = limithara tse 400

Ho potlaka ka lebaka la matla a khoheli (g) = 10 m/s ²

E botsitsoe : Boiteko bo felletseng

Karabo :

Mosebetsi oohle = phetoho ea matla a kinetic

W_kakaretso = ΔEK = ½ m (v_t² - v_o²) = ½ (2)(40² - 20²}

W_kakaretso = ½ (2)(1600 - 400) = 1200 Joule

Karabo e nepahetseng ke C.

9. Ntho e boima ba 2 kg e tsamaya hodima bokahodimo bo boreledi ka lebelo la 2 m/s.^-1Haeba mosebetsi oa li-joule tse 21 o etsoa nthong, lebelo la ntho le tla fetoha ho ba...

A. 1 ms^-1

B. 2 ms^-1

C. 3 ms^-1

D. 5 ms^-1

E. 17 ms^-1

Puisano

Hoa tsebahala hore:

Boima (m) = 2 kg

Lebelo la pele (vo _o ) = 2 m/s

Mosebetsi (W) = 21 Joule

Potso: Lebelo la ho qetela (v _t )

Karabo:

Theorem ea matla a kinetic ea mosebetsi e bolela hore mosebetsi oohle o entsoeng nthong o lekana le phetoho ea matla a kinetic a ntho.

Kakaretso = ΔEK

Kakaretso = 1/2 mv_t² -1/2 mv_o²

Kakaretso = 1/2 m (v_t² - v_o²)

21 = 1/2 (2) (v _t ² – 2 ² )

21 = (v _t ² – 2 ² )

21 = v _t ² – 4

v_t² 21 + 4 = 25

v _t = √25

v _t = 5 m/s

Karabo e nepahetseng ke D.

10. Bolo e boima ba digrama tse 500 e lahlelwa hodimo ho tloha fatshe ka lebelo la pele la 10 ms^-2Haeba g = 10 ms^-2, ebe mosebetsi o etsoang ke matla a khoheli a bolo ha e fihla bophahamong ba eona bo phahameng ke...

A. 2,5 J
B. 5,0 J
C. 25 J
D. 50 J
E. 500 J

Puisano
Hlokomoloha khanyetso ea moea.
Hoa tsebahala :
Boima ba bolo (m) = digrama tse 500 = 0,5 kg
Lebelo la pele (v)_o) = 10 m/s²
Lebelo la ho qetela (v)_t) = 0. Ha e le bophahamong bo phahameng ka ho fetisisa, ntho e ntse e le teng motsotsoana pele e kgutlisa tsela morao.
Ho potlaka ka lebaka la matla a khoheli (g) = 10 m/s²
E botsitsoe : Mosebetsi (W) o etsoang ka boima ba bolo
Jawab :

Khopolo-taba ea matla a kinetic a mosebetsi :
Theorem ea matla a kinetic ea mosebetsi e bolela hore mosebetsi oohle kapa khoebo Foromo ea theorem ea matla a sebetsang le a kinetic bakeng sa matla a hlahang nthong e tšoana le phetoho ea matla a kinetic a ntho.
W_kakaretso = ΔEK = EK_t – EK_o
W_kakaretso = ½ mv_t² – ½ mv_o² = ½ m (v_t² - v_o²)
Lintlha :
EK_t = matla a ho qetela a kinetic, EK_o = matla a kinetic a pele, m = boima ba ntho, v_t = kecepatan pheletso ea ntho, v_o = lebelo la pele la ntho.
Boiteko bo felletseng :
Mosebetsi o etsoang ka boima ba bolo ho tloha nakong eo bolo e lahleloang ho fihlela bolo e fihla bophahamong ba eona bo phahameng ke:
W_kakaretso = ½ m (v_t² - v_o²) = ½ (0,5)(0² - 10²)
W_kakaretso = (0,25)(-100) = -25 Lijoule
Letšoao le lebe le bontša hore tsela eo bolo e tsamaeang ka eona e fapane le tsela eo matla a khoheli a bolo a tsamaeang ka eona. Tsela eo bolo e tsamaeang ka eona e tsamaeang ka eona e ea holimo, ha tsela eo matla a khoheli a bolo a tsamaeang ka eona e le ea tlase. Matla a khoheli Ho etsa mosebetsi o fosahetseng hodima bolo ho bolela hore mosebetsi o etswang ke matla a kgoheli o etsa hore matla a kgoheli a bolo a eketsehe mme matla a kinetic a bolo a fokotsehe. Matla a kgoheli a etsa mosebetsi o motle haeba tataiso ya matla a kgoheli a bolo e tshwana le tataiso ya ho falla ha bolo (bolo e theohela tlase).
Karabo e nepahetseng ke C.

11. Bolo e boima ba 1 kg e lahleloa ntle le lebelo la pele ho tloha holimo ho moaho ho pholletsa le fensetere A mokatong o ka holimo ho ea fensetereng B mokatong o ka tlase ka phapang ea bophahamo ba 2,5 m (g = 10 ms).^-2). Ho hlokahala boiteko bo bokae ho tsamaisa bolo ho tloha fensetereng ya A ho ya fensetereng ya B?

A. 5 Joule
B. 15 Joule
C. 20 Joule
D. 25 Joule
E. 50 Joule

Puisano
Hoa tsebahala :
Boima ba bolo (m) = 1 kg
Lebelo la pele (v)_o) = 0 m/s
Bophahamo (h) = limithara tse 2,5
Ho potlaka ka lebaka la matla a khoheli (g) = 10 m/s²
E botsitsoe : Mosebetsi oohle nakong ea motsamao oa bolo
Jawab :
Lebelo la ho qetela la bolo (v_t)
Bolo e oa ntle le lebelo la pele, kahoo motsamao oa bolo o nkoa e le ho oa ka bolokolohi. Taba ea pele, bala lebelo la ho qetela la bolo u sebelisa foromo. motsamao oa ho oa o lokolohilengHoa tsebahala hore ho potlaka ho bakoang ke matla a khoheli (g) = 10 m/s², phetoho bophahamong ba bolo (h) = limithara tse 2,5 mme lebelo la ho qetela (v) le botsoa_t) ka hona sebelisa mokhoa v_t² = 2 gh
v_t² = 2 gh = 2(10)(2,5) = 2(25)
v_t = √2(25) = 5√2
Kahoo lebelo la ho qetela la bolo ke 5√2 m/s
Mosebetsi oohle = phetoho ea matla a kinetic
W_kakaretso = ΔEK = ½ m (v_t² - v_o²) = ½ (1){(5√2)² - 0²}
W_kakaretso = ½ (25)(2) = 25 Joule
Karabo e nepahetseng ke D.

12. Ntho e boima ba 2 kg qalong e tsamaya ka lebelo la 72 km/h.^-1Kamora ho tsamaya ka lebelo la 400 m, lebelo la ntho le ba 144 km/h.^-1 le (g = 10 ms^-2). Mosebetsi oohle o entsoeng ke ntho eo ka nako eo ke…
A. 20 J
B. 60 J
C. 1.200 J
D. 2.000 J
E. 2.400 J
Puisano
Hoa tsebahala :
Boima ba ntho (m) = 2 kg
Lebelo la pele (v)_o) = 72 km/h = 20 m/s
Lebelo la ho qetela (v)_t) = 144 km/h = 40 m/s
Sebaka se tsamailoeng = limithara tse 400
Ho potlaka ka lebaka la matla a khoheli (g) = 10 m/s²
E botsitsoe : Boiteko bo felletseng
Jawab :
Mosebetsi oohle = phetoho ea matla a kinetic
W_kakaretso = ΔEK = ½ m (v_t² - v_o²) = ½ (2)(40² - 20²}
W_kakaretso = ½ (2)(1600 - 400) = 1200 Joule
Karabo e nepahetseng ke C.

Khopolo-taba ea matla a kinetic a mosebetsi

13. Koloi e boima ba tonne e le 'ngoe, e tloha sebakeng sa phomolo. Ka mor'a nakoana lebelo la eona ke 5 m/s.^-1E kholo khoebo Seo enjene ea koloi e se etsang ke…

A. 1000 Joule
B. 2.500 Joule
C. 5.000 Joule
D. 12.500 Joule
E. 25.000 Joule

Puisano

Hoa tsebahala :
Boima (m) = 1 ton = 1000 kg
Lebelo la pele (v)_o) = 0 (koloi e tsamaya ho tloha boemong bo sa sisinyeheng)
Lebelo la ho qetela (v)_t) = 5 m/s
E botsitsoe : Mosebetsi (W) o etsoang ke enjene ea koloi ke ofe?
Jawab :

Khopolo-taba ea matla a kinetic a mosebetsi:
W_kakaretso = ½ m (v_t² - v_o²)
Mosebetsi o etsoang ke enjene ea koloi ke:
W_kakaretso = ½ (1000)(5² - 0²) = (500)(25 – 0) = (500)(25) = 12.500 Joule
Karabo e nepahetseng ke D.

Khopolo-taba ea Mesebetsi le Matla a Mekaniki

14. Sheba setshwantsho sa motsamao wa dintho tse ka tlase!

Boima ba ntho = 1 kg. Haeba coefficient ea kinetic friction pakeng tsa block le fatše e le 0,2, joale boleng ba ho falla ha ntho ke… g = 10 m/s^2\

A. 10 m
B. 15 m
C. 20 m
D. 25 m
E. 30 m
Puisano:
Hoa tsebahala :
m = 1 kg, g = 10 m/s²,v_o = 10 m/s, v_t = 0
E botsitsoe :
Ho falla ha ntho (lintho) ke eng?
Jawab :
Thuto ea matla a mechini :
Mosebetsi o etsoang ka matla a sa bolokeheng = phetoho ea matla a mechini a ntho.
W_NC = EM₂ – EM₁
W_NC = (EP + EK)₂ – (EP + EK)₁ —- Tekanyo ea 1
Matla a sa bolokeheng a sebetsang nthong ke matla a kinetic friction:
W_NC = f_k s —- Tekanyo ea 2
Mokhoa oa khohlano ea Kinetic :

Nka sebaka sa f_k ho equation ea 2 le f_k ho equation ea 3:
W_NC = f_k s = 2 s
Ha ntho e ntse e tsamaya, e ba le phetoho matleng a kinetic (matla a kinetic aa fokotseha) ha matla a khoheli a ntho a sa fetohe (phetoho matleng a khoheli ke lefela).
W_NC = (EK)₂ – (EK)₁ = ½ mv_t² – ½ mv_o² = ½ m (v_t² - v_o²)
2 s = ½(1)(0² - 10²)
2 s = (0,5)(100)
2 ses = 50
s = 50 / 2 = limithara tse 25
Karabo e nepahetseng ke D.

Molao oa paballo ea matla a mechini

15. Motho ea thellang leqhoeng o thella ho tloha bophahamong ba A joalo ka ha ho bontšitsoe setšoantšong se latelang:
Haeba lebelo la pele la motho ea thellang ka skiing = lefela 'me lebelo le bakoang ke matla a khoheli e le 10 ms^-2, ebe lebelo la sebapali ha se le bophahamong ba B ke...

A. √2 ms^-1
B. 5√2 ms^-1
C. 10√2 ms^-1
D. 20√2 ms^-1
E. 25√2 ms^-1

Puisano
Hoa tsebahala :
Lebelo la pele (v)_o= 0
Ho potlaka ka lebaka la matla a khoheli (g) = 10 m/s²
Phetoho bophahamong = limithara tse 50 - limithara tse 10 = limithara tse 40
E botsitsoe : lebelo la sebapali ha se le bophahamong ba B?
Jawab :
Molao oa paballo ea matla a mechini E bolela seo matla a pele a mechini = matla a ho qetela a mechini.
Ha o qala ho tloha ntlheng ea A, lebelo la pele la motho ea thellang lehloa = v_o = 0 e le hore matla a kinetic a pele = EK_o = ½ mv_o² = 0. Ka lehlakoreng le leng, ha ntlha ea A e fihla, motho ea thellang lehloeng o na le matla a khoheli a pele = EP_o = mgh, moo h = limithara tse 50. Kahoo matla a pele a mechini (EM)_o) = matla a pele a khoheli (EP)_o). Nakong ea motsamao ho tloha ho A ho ea ho B, bophahamo ba motho ea thellang ka har'a lehloa boa fokotseha, kahoo matla a khoheli a fokotseha. Matla a khoheli a ha a lahlehe empa a fetoloa matla a kinetic. Keketseho ea matla a kinetic e bontšoa ke keketseho ea lebelo la motho ea thellang ka har'a lehloa. Haeba motho ea thellang ka har'a lehloa a fihla tlase ho sekamela, matla 'ohle a khoheli a fetoloa matla a kinetic. Botlaaseng ba sekamela, matla a khoheli a ha e lefela, ha matla a kinetic a le holimo haholo. Kahoo matla a ho qetela a mechine (EM) ke_t) = matla a ho qetela a kinetic (EK)_t).

Ho thoe'ng ka matla a khoheli le matla a kinetic ntlheng ea B? Ntlha ea B, matla a mang a khoheli a fokotsoa 'me a fetoloa matla a kinetic. Ka ho khetheha, matla a kinetic ntlheng ea B = phokotso ea matla a khoheli haeba ntho e nkoa e le ho oa ho tloha bophahamong ba limithara tse 40. Hobaneng u sa sebelise bolelele ba sefofane se sekametseng empa u be bolelele ba limithara tse 40? Haeba u sa utloisise sena, u lokela ho ithuta boitsebiso boo hape. matla a bolokang lintho le kamano ea ona le matla a ka bang teng le molao oa paballo ea matla a mechini.

Lebelo la motho ea thellang lehloa bophahamong ba B:
Matla a ho qetela a mechini = matla a pele a mechini
Matla a kinetic ntlheng ea B = matla a khoheli a bophahamo ba limithara tse 40
EK = EP
½ mv_t² = mgh
½ v_t² = gh
½ v_t² = (10)(50-10)
½ v_t² = (10)(40)
½ v_t² = 400
v_t² = (2)(400) = 800
v_t = √800 = √(2)(400) = 20√2 m/s
Karabo e nepahetseng ke D.

16. Ntho e tsamaya ho tloha ntlheng ya A ntle le lebelo la pele. Haeba ho se na kgohlano nakong ya motsamao, lebelo la ntho ntlheng e tlase ke...
A. 8 ms^-1
B. 12 ms^-1
C. 20 ms^-1
D. 24 ms^-1
E. 30 ms^-1
Puisano
Hoa tsebahala :
Boima ba ntho = m
Lebelo la pele (v)_o= 0
Bophahamo (h) = limithara tse 20
Ho potlaka ka lebaka la matla a khoheli (g) = 10 m/s²
E botsitsoe : lebelo la ho qetela (v_t)?
Jawab :
Matla a pele a mechini (EM)₁) = matla a khoheli a ka bang teng ho A (EP)_A) = mgh = (m)(10)(20) = 200 m
Matla a ho qetela a mechini (EM)₂) = matla a kinetic (EK) = ½ mv_t²
Lebelo la ntho ntlheng e tlase ka ho fetisisa kapa lebelo la ho qetela la ntho v_t)?
Molao oa paballo ea matla a mechini:
EM₁ = EM₂
200 m = ½ mv_t²
200 = ½ v_t²
400 = v_t²
v_t= 20 m/s
Karabo e nepahetseng ke C.

 

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