Mohlala oa lipotso tse sekametseng

Mehlala e 9 ea Lipotso tsa Sefofane se Itšetlehileng

Ithute boitsebiso bo mabapi le melao ea Newton , matla a tloaelehileng le matla a khohlano ho utloisisa hamolemo puisano ea potso ena.

1. Boloko ba 5 kg bo lokollwa hodima sekgahla se bataletseng jwalo ka ha ho bontshitswe setshwantshong! (g = 10 ms ⁻² le tg 37 ^o = 3/4). Ho potlaka ha boloko ke...

A. 4,5 ms^-2

B. 6,0 ms ⁻²

C. 7,5 ms ⁻²

D. 8,0 ms ⁻²

E. 10,0 ms ⁻²

Puisano

Hoa tsebahala hore:

m = 5 kg, g = 10 m/s ²

w = mg = (5)(10) = 50 N

bolelele ba lehlakore le ka tlase = 4

bolelele ba lehlakore le otlolohileng = 3

Kaha lehlakore le ka tlase = 4 le lehlakore le otlolohileng = 3 joale hypotenuse = 5. U ka e paka u sebelisa foromo ea Pythagorean.

Potso: ho potlaka ha block (a)?

Karabo:

Matla a etsang hore boloko bo sisinyehe ke w _x . Sefapano se sekametseng se boreleli kahoo ha ho na khohlano.

w_x = sebe θ = (w)(lehlakore le otlolohileng / hypotenuse)

w _x = (50)(3/5)

w _x = 30 Newton

Ho potlakisa (a) ha boloko ke eng?

Σ F = ma

w _x = ma

30 = (5) a

a = 30/5

a = 6 m/s ²

Karabo e nepahetseng ke B.

2. Sheba setshwantsho! Tlolo e qala ka ho phomola, ebe e hulwa ka matla a F ho ya hodimo ho bapile le sefofane se sekametseng. Boima ba boloko ke 8 kg, coefficient ya khohlano µ _s = 0,5 le θ = 45 ^o . Hore boloko e tsamaye hantle ho ya hodimo, matla a F a tlameha ho ba….

A. 40 N

B. 60 N

C. 60√2 N

D. 80 N

E. 80√2 N

Puisano

Hoa tsebahala hore :

Koefficient ea khohlano e sa fetoheng (µs ₎ = 0,5

Sekhutlo (θ) = 45 ^o

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

Boima ba boloko (m) = dikilogerama tse 8

Boima ba boloko (w) = mg = (8 kg)(10 m/s ² ) = 80 kg m/s ² = 80 Newtons

Potso : Boholo ba matla a F hoo boloko bo tla nyolohela hodimo

Karabo :

Boloko bo tla nyolohela hodimo haeba F ≥ w _x + f _s.

Karolo ea matla a khoheli e bapileng le sefofane se sekametseng :

w _x = w sebe θ = (80)(sebe 45) = (80)(0,5√2) = 40√2

Karolo ea matla a khoheli e otlolohileng ho sefofane se sekametseng :

w _y = w cos θ = (80)(cos 45) = (80)(0,5√2) = 40√2

Matla a tloaelehileng :

N = w _y = 40√2

Matla a khohlano a sa fetoheng :

f _s = µ _s N = (0,5)(40√2) = 20√2

Boholo ba matla a F e le hore boloko bo ka nyolohela hodimo :

F ≥ w _x + f _s

F ≥ 40√2 + 20√2

F ≥ 60√2 Newton

Karabo e nepahetseng ke C.

3. Boloko bo boima ba 8 kg bo bewa sebakeng se sekametseng ka tsela e sa tsitsang jwalo ka ha ho bontshitswe setshwantshong se latelang. Matla a ka ntle a hlokahalang ho thibela boloko ho thella ke… (sin 37 ^o = 0,6, cos 37 ^o = 0,8, g = 10 ms ^-2 , µ _k = 0,1)

A. 6,4 N

B. 4,6 N

C. 48,5 N

D. 54,4 N

E. 68,8 N

Puisano

Hoa tsebahala hore :

Boima ba boloko (m) = 8 kg

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

Boima ba boloko (w) = mg = (8)(10) = 80 Newton

Sebe sa 37 ^o = 0,6

Cos 37 ^o = 0,8

Khokahano ea kinetic friction (µ _k ) = 0,1

N = w _y = w cos 37 ^o = (80)(0,8) = 64 Newtons

Potso : Matla a fokolang a kantle (F) a hlokahalang ho tshehetsa boloko e le hore boloko bo se ke ba thella fatshe.

Jawab :

Boloko ha bo thelle fatshe haeba F = w _x

Karolo ea matla a khoheli e bapileng le sefofane se sekametseng :

w _x = w sebe θ = (80)(sebe 37) = (80)(0,6) = 48

f _k = µ _k N = (0,1) (64) = 6,4

Matla a fokolang F e le hore boloko bo se ke ba thella :

F + f _k – w _x = 0

F = w _x – f _k = 48 – 6,4 = 41,6 Li-Newton

4. Ntho e boima ba 5,0 kg e hulwa ka thapo hodimo sefofaneng se sekametseng ka thata ka matla a 71 N (g = 10 ms s ^-2 , sin 37 ^o = 0,6, cos 37 ^o = 0,8). Haeba coefficient ya kgohlano pakeng tsa ntho le sefofane e le 0,4, ho potlaka ho fumanwang ke ntho ke…

A. 0,5 ms^-2

B. 2 ms ^-2

C. 2,5 ms ^-2

D. 3 ms ^-2

E. 5 ms ^-2

Puisano

Hoa tsebahala hore :

Boima ba ntho (m) = 5 kg

4. Lipotso tsa Tlhahlobo ea Naha ea Fisiks ea SMA ea 2012/2013 SA 67 No. 5

Ntho ea boima ba 5,0 kg e huloa ka thapo ho ea holimo sefofaneng se sekametseng ka thata ka matla a 71 N (g = 10 ms s ^-2 , sin 37 ^o = 0,6, cos 37 ^o = 0,8). Haeba coefficient ea khohlano pakeng tsa ntho le sefofane e le 0,4, lebelo le bonoang ke ntho ke…

A. 0,5 ms ^-2

B. 2 ms ^-2

C. 2,5 ms ^-2

D. 3 ms ^-2

E. 5 ms ^-2

Puisano

Hoa tsebahala hore :

Boima ba ntho (m) = 5 kg

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

Boima ba ntho (w) = mg = (5)(10) = 50 Newtons

Matla F = 71 Newton

Sebe sa 37 ^o = 0,6

Cos 37 ^o = 0,8

Khokahano ea khohlano = 0,4

Potso : Ho potlakisa ntho (a)

Karabo :

Matla a Phello

Qala ka ho bala matla a hlahang a sebetsang nthong eo.

Karolo ea matla a khoheli a bapileng le sefofane se sekametseng :

w _x = w sebe θ = (50)(sebe 37) = (50)(0,6) = 30

Karolo ea matla a khoheli e otlolohileng ho sefofane se sekametseng :

w _y = w cos θ = (50)(cos 37) = (50)(0,8) = 40

Mokhoa o tloaelehileng :

N = w _y = 40

Matla a khohlano ea kinetic :

f _k = µ _k N = (0,4)(40) = 16

Matla a hlahang a sebetsang sebakeng se sekametseng:

∑ F = F – w _x – f _k = 71 – 30 – 16 = 25 Newton

Ho potlaka ha ntho

Ho potlaka ha ntho ho balwa ho sebediswa foromo ya molao wa bobedi wa Newton:

a = ∑F / m = 25 / 5 = 5 m/s ²

Karabo e nepahetseng ke E.

5.
Sheba setšoantšo! Lebokose le qala ka ho phomola, ebe le huloa ka matla a holimo F a bapileng le sefofane se sekametsengBoima ba boloko ke 8 kg, coefficient ea khohlano ke µ_s = 0,5 le θ = 45^o. E le hore boloko e nyolohele holimo, matla a F a tlameha ho ba….

A. 40 N
B. 60 N
C. 60√2 N
D. 80 N
E. 80√2 N

Puisano
Hoa tsebahala :
Koefficient khohlano e sa fetoheng (µ_s= 0,5
Sekhutlo (θ) = 45^o
Ho potlaka ka lebaka la matla a khoheli (g) = 10 m/s²
Boima ba boloko (m) = dikilogerama tse 8
Boima ba boloko (w) = mg = (8 kg)(10 m/s²) = 80 kg m/s² = 80 Newton
E botsitsoe : Boholo ba matla a F hoo boloko bo tla nyolohela hodimo
Jawab :

Boloko bo nepahetseng bo tla nyoloha haeba F ≥ w_x + f_s.
Karolo ea matla a khoheli e bapileng le sefofane se sekametseng :
w_x = w sebe θ = (80)(sebe 45) = (80)(0,5√2) = 40√2
Karolo ea matla a khoheli e otlolohileng ho sefofane se sekametseng :
w_y = w cos θ = (80)(cos 45) = (80)(0,5√2) = 40√2
Matla a tloaelehileng :
N = w_y = 40√2
Matla a khohlano a sa fetoheng :
f_s = µ_s N = (0,5)(40√2) = 20√2
Boholo ba matla a F e le hore boloko bo ka nyolohela hodimo :
F ≥ w_x + f_s
F ≥ 40√2 + 20-2
F ≥ 60√2 Newton
Karabo e nepahetseng ke C.

6.
Sekotwana se boima ba 8 kg se beoa sebakeng se sekametseng ka thata jwalo ka ha ho bontshitswe setshwantshong se ka tlase. Matla a fokolang a kantle a hlokahalang ho thibela sekotwana ho thella ke… (sebe sa 37^o = 0,6, cos 37^o = 0,8, g = 10 ms^-2, µ_k = 0,1)

A. 6,4 N
B. 4,6 N
C. 48,5 N
D. 54,4 N
E. 68,8 N

Puisano
Hoa tsebahala :
Boima ba boloko (m) = 8 kg
Ho potlaka ka lebaka la matla a khoheli (g) = 10 m/s²
Boima ba boloko (w) = mg = (8)(10) = 80 Newton
Sebe sa 37^o = 0,6
Tše 37^o = 0,8
Khokahano ea kinetic ea khohlano (µ_k= 0,1
E botsitsoe : Matla a ka ntle a bonyane (F) a tšoereng boloko e le hore boloko bo se ke ba thella
Jawab :
Boloko ha bo thellele tlase haeba F = w_x
Karolo ea matla a khoheli e bapileng le sefofane se sekametseng :
w_x = w sebe θ = (80)(sebe 37) = (80)(0,6) = 48
f_k = µ_k N = (0,1)(64) = 6,4
Matla a fokolang F e le hore boloko bo se ke ba thella :
F + f_k - w_x = 0
F = w_x - f_k = 48 – 6,4 = 41,6 Newton

7.
Ntho e boima ba 5,0 kg e hulwa ka thapo hodimo sebakeng se sekametseng ka matla a 71 N (g = 10 ms s).^-2, sebe sa 37^o = 0,6, cos 37^o = 0,8). Haeba coefficient ea khohlano pakeng tsa ntho le sefofane e le 0,4, lebelo le bonoang ke ntho ke…
A. 0,5 ms^-2
B. 2 ms^-2
C. 2,5 ms^-2
D. 3 ms^-2
E. 5 ms^-2
Puisano
Hoa tsebahala :
Boima ba ntho (m) = 5 kg
Ho potlaka ka lebaka la matla a khoheli (g) = 10 m/s²
Boima ba ntho (w) = mg = (5)(10) = 50 Newtons
Matla F = 71 Newton
Sebe sa 37^o = 0,6
Tše 37^o = 0,8
Khokahano ea khohlano = 0,4
E botsitsoe Ho potlaka ha ntho (a)
Jawab :
Matla a Phello
Qala ka ho bala matla a hlahang a sebetsang nthong eo.
Karolo ea matla a khoheli e bapileng le sefofane se sekametseng :
w_x = w sebe θ = (50)(sebe 37) = (50)(0,6) = 30
Karolo ea matla a khoheli e otlolohileng ho sefofane se sekametseng :
w_y = w cos θ = (50)(cos 37) = (50)(0,8) = 40
Matla a tloaelehileng :
N = w_y = 40
Matla a khohlano a Kinetic :
f_k = µ_k N = (0,4)(40) = 16
Matla a hlahang a sebetsang sebakeng se sekametseng:
∑F = F – w_x - f_k = 71 – 30 – 16 = 25 Li-Newton
Ho potlaka ha ntho
Ho potlaka ha ntho ho balwa ho sebediswa foromo ya molao wa bobedi wa Newton:
a = ∑F / m = 25 / 5 = 5 m/s²
Karabo e nepahetseng ke E.

8. Sheba setshwantsho! Tlolo e qala ka ho phomola, ebe e hulwa ka matla a F ho ya hodimo ho bapile le sefofane se sekametseng. Boima ba boloko ke 2 kg, coefficient ya static friction = 0,3 mme angle = 45 ^o . Hore boloko e tsamaye hantle ho ya hodimo, matla a F a tlameha ho ba… g = 10 m/s ²

Puisano
Hoa tsebahala hore:
m = 2 kg, g = 10 m/s², = 45^o, μ_s = 0,3
Potso: E le hore boloko bo tsamaee hantle ho ea holimo, matla a F a maholo hakae?
Karabo:

Tlhahisoleseding: F = matla a ho tsikinyeha, w = matla a kgoheli, w_x = karolo ea boima ba boloko e bapileng le bokaholimo ba sefofane se sekametseng, w_y = karolo ea boima ba boloko e otlolohileng holim'a sefofane se sekametseng, N = matla a tloaelehileng, f_s = matla a khohlano a sa fetoheng.

Potsong ena, coefficient ea khohlano e sa fetoheng e tsejoa, sena se bolela hore bokaholimo ba sefofane se sekametseng bo makukuno hoo ho nang le matla a khohlano a thibelang motsamao oa block.
E le hore boloko e nyolohele holimo, matla a F a tlameha ho lekana le w._x +f_sNtho e nyolohela hodimo ha F e le kgolo ho feta w_x +f_s.

w = mg = (2)(10) = 20 Newtons
w_x = sebe sa 45^o = (20)(½ √2) = 10√2 Li-Newton
w_y = w cos 45^o = (20)(½√2) = 10√2 Li-Newton
N = w_y = 10√2
f_s = μ_s N = (0,3)(10√2) = 3√2 Li-Newton

E le hore boloko e tla nyolohela holimo ka nako eo:
F = w_x +f_s = 10√2 + 3√2= 13√2 Li-Newton
Karabo e nepahetseng ke C.

9. Ntho e boima ba 2 kg e beoa sebakeng se sekametseng joalo ka ha ho bontšitsoe setšoantšong se ka tlase. Haeba coefficient ea khohlano e sa fetoheng pakeng tsa boloko le sebaka se sekametseng e le 0,2√3 le g = 10 ms ^–2 , joale matla a hlahang a tsamaisang ntho ke…

Puisano
Hoa tsebahala hore:
m = 2 kg, g = 10 m/s², = 30^o, μ_s = 0,2√3
Botsitswe: Matla a hlahang a tsamaisang ntho?

Karabo:

Khohlano e lula e thibela motsamao oa ntho, ka hona tataiso ea matla a khohlano e bontšoa e le khahlanong le tataiso ea motsamao oa ntho. Ntho e nkoa e le e theohelang tlaase, kahoo matla a khohlano a bontšoa e le a holimo. Ntho e nkoa e le e theohelang tlaase hobane ha ho na matla a e hulang holimo.
w = mg = (2)(10) = 20 Newtons
w_x = sebe sa 30^o = (20)(½) = 10 Newton
w_y = w cos 30^o = (20)(½ √3) = 10√3 Li-Newton
N = w_y = 10√3 Newton
f_s = μ_s N = (0,2√3)(10√3) = (2)(3) = 6 Newtons
Matla a hlahang a tsamaisang ntho ke:
F = w_x - f_s = 10 – 6 = 4 Newton
w_x e kholo ho feta f_s kahoo ntho e theohela tlase, ka lehlakoreng la w_x.
Karabo e nepahetseng ke A.

Mohloli oa lipotso:

Lipotso tsa Fisiks tsa Tlhahlobo ea Naha bakeng sa Sekolo se Phahameng sa Thuto e Phahameng/Sekolo se Phahameng sa Mosebetsi