Kev sib npaug ntawm cov cev txuas nrog los ntawm cov hlua thiab pulleys - kev siv Newton txoj cai thawj zaug cov teeb meem thiab kev daws teeb meem

1. Ib lub thawv hnyav 5 kg nyob rau ntawm ib lub dav hlau uas nkhaus ntawm lub kaum sab xis 30 ° . Lub thawv muaj ib txoj hlua txhawb. Txheeb xyuas lub zog nruj (T) thiab lub zog ib txwm (N)!

Kev sib npaug ntawm cov cev txuas nrog los ntawm cov hlua thiab pulleys - kev siv Newton txoj cai thawj zaug cov teeb meem thiab kev daws teeb meem 1

tshuaj

Kev sib npaug ntawm cov cev txuas nrog los ntawm cov hlua thiab pulleys - kev siv Newton txoj cai thawj zaug cov teeb meem thiab kev daws teeb meem 2∑Fx = 0

T – w sin 30 o = 0

T = w sin 30 o

T = (5 kg)(9.8 m/s 2 ) sin 30 o

T = (49)(0.5)

T = 24.5 Newtons

∑ Fy = 0

N – w cos 30 o = 0

N = w cos 30 o

N = (49)(0.87)

N = 43 Newtons

[irp]

2. Ob yam khoom uas hnyav m 1 = m 2 = 2 kg, txuas nrog ib txoj hlua tsis muaj hnyav hla lub pulley tsis muaj kev sib txhuam. Nrhiav cov zog nruj T 1 thiab T 2.

Kev sib npaug ntawm cov cev txuas nrog los ntawm cov hlua thiab pulleys - kev siv Newton txoj cai thawj zaug cov teeb meem thiab kev daws teeb meem 3

tshuaj

Kev sib npaug ntawm cov cev txuas nrog los ntawm cov hlua thiab pulleys - kev siv Newton txoj cai thawj zaug cov teeb meem thiab kev daws teeb meem 4

(a) Daim duab qhia txog lub cev dawb rau yam khoom 1 (b) Daim duab qhia txog lub cev dawb rau yam khoom 2

Siv Newton txoj cai thib ib rau yam khoom 1:

∑ Fy = 0

T 1 – w 1 = 0

T 1 = w 1 = m 1 g = (2 kg)(9.8 m/s 2 ) = 19.6 N

Siv txoj cai lij choj thib ib ntawm Newton rau yam khoom 2:

∑ Fy = 0

T 2 – w 2 = 0

T2 = w2 = m2 g = ( 2 kg)(9.8 m/s2 ) = 19.6 N

T 1 = T 2 = 19.6 N.

[irp]

3. Ib yam khoom uas hnyav w A = 30 N thiab ib yam khoom uas hnyav w B = 40 N, raug khi los ntawm ib txoj hlua sib dua uas hla lub pulley uas tsis muaj kev sib txhuam ntawm qhov hnyav me me. Txheeb xyuas tus coefficient ntawm qhov sib txhuam zoo tshaj plaws ntawm w B thiab qhov chaw inclined, yog tias lub kaw lus nyob twj ywm.

Kev sib npaug ntawm cov cev txuas nrog los ntawm cov hlua thiab pulleys - kev siv Newton txoj cai thawj zaug cov teeb meem thiab kev daws teeb meem 5

tshuaj

Kev sib npaug ntawm cov cev txuas nrog los ntawm cov hlua thiab pulleys - kev siv Newton txoj cai thawj zaug cov teeb meem thiab kev daws teeb meem 6

(a) Daim duab qhia txog lub cev dawb rau yam khoom w A (b) Daim duab qhia txog lub cev dawb rau yam khoom w B

Siv Newton txoj cai thawj zaug rau yam khoom w A hauv kev taw qhia ntsug (y):

∑ F y = 0 (tsis muaj kev nrawm hauv kev taw qhia ntsug)

T – w A = 0

T = w A = 30 Newton

Siv Newton txoj cai thawj zaug rau yam khoom w B hauv kev taw qhia ntsug (y) :

∑ Fy = 0

N – w B cos 45 o = 0

N = w B cos 45 o = (40)(0.7) = 28 Newtons

Siv Newton txoj cai thawj zaug rau yam khoom w B hauv kab rov tav (x):

∑ F x = 0

Fk + wB sin 45 o – T = 0

μ s N + w B sin 45 o – T = 0

μs (28) + (40)(0.7) - 30 = 0

μ s (28) + 28 – 30 = 0

μs (28) = 30 – 28

μs (28) = 2

μs = 2 / 28

μs = 0.07

Tus coefficient ntawm qhov siab tshaj plaws static friction ntawm w B thiab inclined surface = 0.07.

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  1. Cov khoom me me hauv ib qho kev sib npaug
  2. Cov khoom me me hauv qhov sib npaug ob sab
  3. Kev sib npaug ntawm lub cev txuas nrog los ntawm cov hlua thiab pulleys
  4. Kev sib npaug ntawm lub cev ntawm lub dav hlau inclined

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