Hauv kev siv lub cev, kev nruj yog lub zog ua los ntawm txoj hlua, xov, cable, lossis lwm yam khoom zoo sib xws ntawm ib lossis ntau yam khoom. Txhua yam khoom uas rub, dai, tuav, lossis swung los ntawm txoj hlua, xov, thiab lwm yam yog raug rau qhov nruj. Raws li nrog txhua lub zog, kev nrawm tuaj yeem ua kom nrawm ib yam lossis ua rau nws deform. Lub peev xwm los suav qhov kev nyuaj siab yog qhov tseem ceeb tsis yog rau cov tub ntxhais kawm ntawv kawm txog physics, tab sis kuj yog rau cov kws tsim txuj ci thiab kws tsim vaj tsev. Txhawm rau tsim lub tsev muaj kev nyab xeeb lawv yuav tsum muaj peev xwm txiav txim siab tias qhov nro hauv ib txoj hlua tshwj xeeb lossis kab hluav taws xob tuaj yeem tiv taus qhov mob tshwm sim los ntawm qhov hnyav ntawm ib yam khoom ua ntej nws nthuav thiab tawg. Saib Kauj Ruam 1 kom kawm paub xam xam kev ntxhov siab hauv qee lub cev.
Kauj ruam
Txoj Kev 1 ntawm 2: Kev Txiav Txim Siab ntawm Ib Kawg Ntawm Txoj hlua
Kauj Ruam 1. Txiav txim siab qhov kawg ntawm txoj hlua
Qhov nro hauv txoj hlua yog qhov tshuaj tiv thaiv rau kev rub lub zog ntawm txhua qhov kawg ntawm txoj hlua. Raws li kev ceeb toom, quab yuam = pawg × nrawm. Piv txwv tias txoj hlua raug rub kom txog thaum nws nruj, txhua qhov kev hloov pauv hauv qhov nrawm lossis qhov hnyav ntawm cov khoom uas tau tuav los ntawm txoj hlua yuav ua rau muaj kev hloov pauv ntawm qhov nro ntawm txoj hlua. Tsis txhob hnov qab qhov nrawm nrawm vim yog lub ntiajteb txawj nqus-txawm tias lub kaw lus tau so lawm; nws lub Cheebtsam yog raug rau lub ntiajteb txawj nqus. Qhov nro hauv txoj hlua tuaj yeem xam los ntawm T = (m × g) + (m × a); "g" yog qhov nrawm vim qhov nqus ntawm qhov khoom tuav los ntawm txoj hlua thiab "a" yog lwm qhov nrawm ntawm cov khoom uas tuav los ntawm txoj hlua.
- Yuav luag txhua qhov teeb meem ntawm lub cev, peb xav tias yog txoj hlua zoo tshaj plaws - hauv lwm lo lus, hlua lossis cable, lossis lwm yam, peb xav tias nyias nyias, tsis muaj qhov hnyav, tsis ncab lossis puas.
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Piv txwv, xav txog qhov system; qhov hnyav raug tshem tawm ntawm tus ntoo khaub lig los ntawm txoj hlua (saib daim duab). Tsis yog yam khoom lossis txoj hlua txav mus-tag nrho cov kab ke tau so. Yog li ntawd, peb tuaj yeem hais tias lub nra nyob hauv qhov sib npaug kom lub zog nrawm yuav tsum sib npaug nrog lub zog nqus ntawm qhov khoom. Hauv lwm lo lus, Voltage (Ft) = lub zog nqus (Fg) = m × g.
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Xav tias qhov hnyav ntawm 10 kg, tom qab ntawd qhov nro hauv txoj hlua yog 10 kg × 9.8 m/s2 = 98 Newton mus.
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Kauj Ruam 2. Xam nrawm
Lub ntiajteb txawj nqus tsis yog lub zog nkaus xwb uas tuaj yeem cuam tshuam rau qhov nrawm hauv txoj hlua-yog li txhua lub zog uas ua kom nrawm dua ib yam khoom uas txoj hlua tuav tau tuaj yeem cuam tshuam rau nws. Yog tias, piv txwv li, ib yam khoom dai ntawm txoj hlua raug nrawm los ntawm kev quab yuam ntawm txoj hlua lossis cable, qhov nrawm nrawm (pawg × nrawm) ntxiv rau qhov kev nyuab siab los ntawm qhov khoom hnyav.
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Piv txwv li, hauv peb qhov piv txwv ib yam khoom nrog qhov hnyav ntawm 10 kg yog dai los ntawm txoj hlua es tsis txhob dai ntawm tus ntoo ntoo. Cov hlua raug rub nrog kev nrawm nce ntawm 1 m/s.2. Hauv qhov no, peb yuav tsum coj mus rau hauv tus account qhov ua kom nrawm dhau los ntawm cov khoom uas tsis yog lub zog ntawm lub ntiajteb txawj nqus nrog cov lej hauv qab no:
- Ft = Fg + m × ua
- Ft = 98 + 10 kg × 1 m/s2
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Ft = 108 Newton mus.
Kauj Ruam 3. Xam lub kaum sab xis nrawm
Ib yam khoom txav ib puag ncig nruab nrab los ntawm txoj hlua (xws li pendulum) ua rau muaj kev nruj ntawm txoj hlua vim yog lub zog centripetal. Lub zog centripetal yog qhov nrawm ntxiv hauv txoj hlua uas tshwm sim los ntawm "rub" sab hauv kom cov khoom txav mus rau hauv lub voj voog tsis txhob txav mus rau hauv txoj kab ncaj. Cov khoom txav mus nrawm dua, lub zog centripetal ntau dua. Centripetal quab yuam (F.c) yog sib npaug rau m × v2/r; "m" yog huab hwm coj, "v" yog qhov nrawm, thiab "r" yog lub vojvoog ntawm cov lus tsa suab ncig ntawm qhov khoom.
- Txij li qhov kev taw qhia thiab qhov loj ntawm lub zog centripetal hloov pauv raws li cov khoom raug tshem tawm thiab hloov nws qhov nrawm, yog li tag nrho qhov nrawm ntawm txoj hlua, uas ib txwm ua tib zoo sib txuas rau txoj hlua rub cov khoom mus rau qhov nruab nrab ntawm kev sib hloov. Nco ntsoov tias lub zog ntawm kev nqus ib txwm ua rau cov khoom nqes. Yog li, thaum cov khoom tig los yog viav vias ntsug, tag nrho cov kev nyuaj siab yog qhov zoo tshaj plaws ntawm qhov qis tshaj ntawm lub arc (ntawm lub pendulum lub ntsiab lus no hu ua qhov sib npaug sib npaug) thaum cov khoom txav mus nrawm tshaj plaws thiab qis tshaj ntawm qhov siab tshaj plaws ntawm lub arc thaum cov khoom txav mus tshaj qhov qeeb.
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Hauv peb qhov piv txwv, lub hom phiaj tsis txuas ntxiv mus kom nrawm tab sis viav vias zoo li lub pendulum. Piv txwv tias qhov ntev ntawm txoj hlua yog 1.5 m ntev thiab cov khoom tau txav nrog qhov nrawm ntawm 2 m/s thaum nws hla dhau qhov qis tshaj ntawm qhov viav vias. Yog tias peb xav xam qhov kev nyuab siab ntawm qhov qis tshaj ntawm qhov viav vias, piv txwv li qhov kev ntxhov siab tshaj plaws, peb yuav tsum xub paub tias qhov kev ntxhov siab vim lub ntiajteb txawj nqus ntawm qhov no yog tib yam li thaum cov khoom nyob ruaj ruaj-98 Newtons. Txhawm rau nrhiav lub zog centripetal ntxiv, peb tuaj yeem suav nws raws li hauv qab no:
- Fc = m × v2/r ib
- Fc = 10 × 22/1, 5
- Fc 10 × 2.67 = 26.7 Newtons
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Yog li, tag nrho kev ntxhov siab yog 98 + 26, 7 = 124, 7 Newton
Kauj Ruam 4. Nkag siab tias qhov kev nyuab siab vim lub ntiajteb txawj nqus hloov pauv mus raws lub viav vias
Raws li tau hais los saum no, ob qho kev taw qhia thiab qhov loj ntawm lub zog centripetal hloov pauv raws li cov khoom siv viav vias. Txawm li cas los xij, txawm hais tias lub zog quab yuam tseem nyob tas li, qhov kev nyuab siab vim lub ntiajteb txawj nqus tseem hloov pauv. Thaum qhov khoom viav vias tsis nyob ntawm nws qhov qis tshaj ntawm qhov viav vias (nws qhov sib npaug sib npaug), lub ntiajteb txawj nqus rub nws qis, tab sis kev nrawm nrawm rub nws ntawm lub kaum ntse ntse. Yog li ntawd, kev ntxhov siab tsuas yog ua rau ib feem ntawm lub zog tshwm sim los ntawm lub ntiajteb txawj nqus, tsis yog rau txhua qhov.
- Rhuav lub zog ntawm lub ntiajteb txawj nqus rau hauv ob lub vectors los pab koj pom lub tswvyim no. Ntawm txhua lub ntsiab lus hauv kev txav ntawm cov khoom viav vias ntsug, txoj hlua ua lub kaum sab xis "θ" nrog txoj kab hla dhau qhov sib npaug thiab qhov nruab nrab ntawm cov lus tsa suab. Raws li lub pendulum viav vias, lub zog nqus (m × g) tuaj yeem faib ua ob lub vectors-mgsin (θ) uas nws qhov kev taw qhia yog tangent rau lub arc ntawm qhov kev ua viav vias thiab mgcos (θ) uas zoo ib yam thiab sib thooj rau qhov quab yuam. Qhov kev nyuab siab tsuas yog yuav tsum tau tawm tsam mgcos (θ)-lub zog rub nws-tsis yog tag nrho lub zog nqus (tshwj tsis yog ntawm qhov sib npaug; lawv yog tus nqi zoo ib yam).
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Piv txwv li, thaum lub pendulum ua lub kaum sab xis ntawm 15 degrees nrog txoj kab ntsug, nws txav nrog kev nrawm ntawm 1.5 m/s. Qhov hluav taws xob tuaj yeem xam raws li hauv qab no:
- Kev nyuaj siab vim lub ntiajteb txawj nqus (T.g) = 98cos (15) = 98 (0, 96) = 94, 08 Newton
- Centripetal quab yuam (F.c) = 10 × 1, 521, 5 = 10 × 1.5 = 15 Newtons
- Tag nrho kev ntxhov siab = Tg + Fc = 94, 08 + 15 = 109, 08 Newtons.
Xam Tension hauv Physics Kauj Ruam 5 Kauj Ruam 5. Xam kev sib txhuam
Txhua qhov khoom raug rub los ntawm txoj hlua uas paub txog "kev tiv thaiv" quab yuam los ntawm kev sib txhuam rau lwm yam khoom (lossis kua) xa cov quab yuam no mus rau qhov nro hauv txoj hlua. Kev sib txhuam ntawm ob yam khoom tuaj yeem xam raws li lwm qhov xwm txheej-ua raws cov kab zauv hauv qab no: Lub zog sib txhuam (feem ntau sau ua Fr) = (mu) N; mu yog qhov coefficient ntawm kev sib txhuam ntawm ob yam khoom thiab N yog qhov quab yuam ib txwm muaj ntawm ob yam khoom, lossis qhov quab yuam uas ob yam khoom sib tsoo ntawm ib leeg. Nco ntsoov tias kev sib txhuam zoo li qub (uas yog, kev sib txhuam uas tshwm sim thaum cov khoom ruaj khov txav) txawv ntawm kev sib txhuam kinetic (kev sib txhuam uas tshwm sim thaum cov khoom txav mus los).
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Piv txwv li, qhov khoom qub nrog qhov hnyav ntawm 10 kg tsis raug dai ntxiv lawm, tab sis raug rub los ntawm txoj kab hauv av. Piv txwv li, av muaj qhov sib npaug ntawm kev sib txhuam ntawm 0.5 thiab cov khoom txav mus los ntawm qhov nrawm, tom qab ntawd nrawm dua 1 m/s2. Qhov teeb meem tshiab no nthuav tawm ob qhov kev hloov pauv-ua ntej, peb tsis tas yuav suav qhov nyuaj siab vim lub ntiajteb txawj nqus vim txoj hlua tsis txhawb nqa qhov hnyav ntawm qhov khoom. Qhov thib ob, peb yuav tsum coj mus rau hauv tus account qhov kev ntxhov siab vim kev sib txhuam, ntxiv rau qhov tshwm sim los ntawm kev nrawm ntawm lub cev loj. Qhov teeb meem no tuaj yeem daws tau raws li hauv qab no:
- Ib txwm quab yuam (N) = 10 kg × 9.8 (nrawm ntawm lub ntiajteb txawj nqus) = 98 N
- Lub zog ntawm kev sib txhuam kinetic (F.r) = 0.5 × 98 N = 49 Newton
- Kev quab yuam los ntawm kev nrawm (F.a) = 10 kg × 1 m/s2 10 Newtons
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Kev nyuab siab tag nrho = F.r + Fa = 49 + 10 = 5 9 Newton
Txoj Kev 2 ntawm 2: Xam Tension Ntau Tshaj Ib Leeg
Xam Tension hauv Physics Kauj Ruam 6 Kauj Ruam 1. Nqa qhov hnyav ntsug siv lub laub
Lub pulley yog lub tshuab yooj yim suav nrog lub disk tshem tawm uas tso cai hloov pauv hauv kev coj ntawm lub zog nrawm ntawm txoj hlua. Hauv cov txheej txheem yooj yooj yim, txoj hlua khi rau ib yam khoom raug tsa ntawm tus rub txoj hlua, tom qab ntawd nqes rov qab kom nws faib txoj hlua ua ob txoj hlua dai. Txawm li cas los xij, qhov nrawm ntawm ob txoj hlua tseem zoo ib yam, txawm tias thaum ob txoj hlua kawg tau rub nrog lub zog sib txawv. Rau cov kab ke nrog ob pawg neeg dai rau ntawm kab ntsig ntsug, qhov kev nyuab siab sib npaug li 2g (m1) (kuv2)/(m os2+m1); "g" yog qhov nrawm vim lub ntiajteb txawj nqus, "m1"yog qhov hnyav ntawm qhov khoom 1, thiab" m2"yog qhov hnyav ntawm qhov khoom 2.
- Nco ntsoov tias teeb meem kev siv lub cev xav tias yog lub cuab yeej zoo tshaj plaws - lub log uas tsis muaj qhov hnyav, tsis muaj kev sib txhuam, tsis tuaj yeem tawg, deform, lossis tshem tawm ntawm cov dai, hlua, lossis yam uas tuav nws hauv qhov chaw.
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Piv txwv tias peb muaj ob yam khoom dai ntsug ntawm lub pulley nrog cov hlua sib dhos. Yam khoom 1 muaj qhov hnyav ntawm 10 kg, thaum cov khoom 2 muaj qhov hnyav ntawm 5 kg. Hauv qhov no, qhov hluav taws xob tuaj yeem xam raws li hauv qab no:
- T = 2g (m1) (kuv2)/(m os2+m1)
- T = 2 (9, 8) (10) (5)/(5 + 10)
- T = 19, 6 (50)/(15)
- Luas = 980/15
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T = tau 65,33 Newtons.
- Nco ntsoov tias ib yam khoom hnyav dua li lwm qhov, lwm yam sib npaug, lub kaw lus yuav nrawm dua, nrog 10 kg cov khoom txav mus thiab 5 kg cov khoom txav mus.
Kauj Ruam 2. Nqa qhov hnyav siv lub laub nrog txoj hlua ntsug tsis ncaj
Pulleys feem ntau siv los qhia qhov nrawm nyob rau hauv ib qho kev qhia uas tsis yog nce lossis nqis. Piv txwv li, qhov hnyav dai ntawm ib qho kawg ntawm txoj hlua thaum lwm qhov kawg qhov khoom thib ob dai ntawm qhov nqes hav inclined; Qhov txheej txheem tsis sib dhos no yog nyob rau hauv daim duab ntawm daim duab peb sab uas nws cov ntsiab lus yog thawj yam khoom, qhov khoom thib ob, thiab cov menyuam. Hauv qhov no, qhov nrawm ntawm txoj hlua raug cuam tshuam los ntawm ob lub zog nqus ntawm qhov khoom thiab tiv thaiv kev rub lub zog ntawm txoj hlua txuas mus rau txoj kab nqes.
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Piv txwv li, cov kab ke no muaj qhov hnyav ntawm 10 kg (m1) dai ntsug tau txuas nrog ntawm lub pulley mus rau qhov khoom thib ob ntawm qhov hnyav 5 kg (m2) ntawm txoj kab nqes ntawm 60 degrees (xav tias txoj kab nqes hav tsis muaj kev sib txhuam). Txhawm rau suav qhov nrawm ntawm txoj hlua, txoj hauv kev yooj yim tshaj plaws yog nrhiav qhov sib npaug rau qhov khoom uas ua rau nrawm nrawm ua ntej. Cov txheej txheem yog raws li hauv qab no:
- Cov khoom raug tshem tawm hnyav dua thiab tsis muaj kev sib txhuam, yog li peb tuaj yeem suav nws qhov nrawm dua. Qhov nro hauv txoj hlua rub nws kom siab li ntawd nws yuav muaj qhov tshwm sim quab yuam F = m1(g) - T, lossis 10 (9, 8) - T = 98 - T.
- Peb paub tias ib yam khoom ntawm qhov nqes hav yuav ua kom nce nqes hav. Txij li txoj kab nqes hav tsis muaj kev sib txhuam, peb paub tias qhov nrawm ntawm txoj hlua rub nws thiab tsuas yog qhov hnyav nws tus kheej tab tom rub nws. Qhov tivthaiv ntawm lub zog rub nws nqes hav yog kev txhaum (θ); yog li hauv qhov no, qhov khoom yuav ua kom nrawm dua qhov nqes nrog qhov tshwm sim quab yuam F = T - m2(g) sin (60) = T - 5 (9, 8) (0, 87) = T - 42, 63.
- Kev nrawm ntawm ob yam khoom no zoo ib yam kom (98 - T)/m1 = (T - 42, 63) /m2. Los ntawm kev daws qhov sib npaug no, peb yuav tau txais T = 60, 96 Newtons.
Xam Tension hauv Physics Kauj Ruam 8 Kauj Ruam 3. Siv ntau tshaj ib txoj hlua los dai khoom
Thaum kawg, peb yuav saib ib yam khoom dai ntawm lub qab nthab nrog txoj kab hlua "Y-shaped", ntawm lub hauv paus taw tes dai txoj hlua thib peb tuav lub khoom. Qhov nrawm ntawm txoj hlua thib peb yog qhov pom tseeb-tsuas yog muaj kev nruj los ntawm lub zog nqus, lossis m (g). Qhov kev sib tw ntawm ob txoj hlua sib txawv yog qhov sib txawv thiab thaum ntxiv ua ke hauv txoj kab ntsug yuav tsum sib npaug ntawm lub zog nqus thiab sib npaug rau xoom thaum ntxiv rau hauv kab rov tav, yog tias lub kaw lus tsis txav mus. Qhov nro hauv txoj hlua raug cuam tshuam los ntawm qhov hnyav ntawm cov khoom dai thiab los ntawm lub kaum sab xis ntawm txoj hlua thiab qab nthab.
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Piv txwv li, Y-lub cev tau ntim nrog qhov hnyav ntawm 10 kg ntawm ob txoj hlua dai ntawm lub qab nthab ntawm kaum ntawm 30 degrees thiab 60 degrees. Yog tias peb xav pom qhov nrawm ntawm ob txoj hlua sab saud, peb yuav tsum tau coj mus rau hauv tus account cov khoom ntawm qhov nrawm ntawm cov lus qhia ntsug thiab kab rov tav, feem. Txawm li cas los xij, hauv qhov ua piv txwv no, ob txoj hlua dai ua lub kaum sab xis, ua kom yooj yim dua rau peb los xam raws li lub ntsiab lus ntawm kev ua haujlwm trigonometric raws li hauv qab no:
- Kev sib piv ntawm T.1 lub T.2 thiab T = m (g) yog sib npaug sine ntawm lub kaum sab xis nruab nrab ntawm ob txoj hlua tuav cov khoom thiab qab nthab. Rau T.1, kev txhaum (30) = 0, 5, thaum rau T2sin (60) = 0.87
- Muab qhov nro hauv txoj hlua hauv qab (T = mg) los ntawm sine rau txhua lub kaum sab xis los xam T1 thiab T.2.
- T1 = 0.5 × m (g) = 0.5 × 10 (9, 8) = 49 Newton mus.
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T2 = 0.87 × m (g) = 0.87 × 10 (9, 8) = 85, 26 Newtons.
