Nthawi ya mphamvu

Nkhani yokhudza Moment of Force

1. Dzanja la lever

Unikani chinthu chomwe chimazungulira, monga chitseko cha chipinda. Chitseko chikatsegulidwa kapena kutsekedwa, chitsekocho chimazungulira. Ma hinge omwe amalumikiza chitseko ndi khoma amagwira ntchito ngati mzere wozungulira.

Chithunzi cha chitseko chikuwoneka kuchokera pamwamba. Unikani chitsanzo pomwe chitseko chimakankhidwira m'mphamvu ziwiri zomwezo zomwe zili ndi kukula ndi njira yofanana, komwe njira ya mphamvuyo ili molunjika ku chitseko. Poyamba, chitseko chimakankhidwira ndi mphamvu ya F₁, r₁ kuchokera ku mzere wozungulira. Pambuyo pake, chitseko chimakankhidwa ndi mphamvu ya F₂, r₂ kutali ndi mzere wozungulira. Ngakhale kukula ndi malangizo a mphamvu F₁ =F₂, mphamvu ya F₂ zimapangitsa kuti chitseko chizungulire mofulumira kuposa mphamvu ya F₁Mwa kuyankhula kwina, mphamvu ya F₂ zimayambitsa kuthamanga kwakukulu kwa angular poyerekeza ndi mphamvu ya F₁Mukhoza kutsimikizira izi.

Kukula kwa liwiro la angular la chinthu choyenda sikumangokhudzidwa ndi mphamvu yokha komanso kumakhudzidwa ndi mtunda pakati pa mfundo zogwirira ntchito za mphamvu ndi mzere wozungulira (r). Ngati malangizo a mphamvu ali olunjika pamwamba pa chinthu monga momwe zilili pachitsanzo pamwambapa, ndiye kuti mkono wa lever (l) ndi wofanana ndi mtunda pakati pa mfundo zogwirira ntchito ndi mzere wozungulira (r). Nanga bwanji ngati malangizo a mphamvu sali olunjika pamwamba pa chinthucho?

Unikaninso zitsanzo zina ziwiri, monga momwe zasonyezedwera pachithunzi chomwe chili pambali. Ngakhale kukula kwa mphamvu kuli kofanana, komwe mphamvuyo ikupita ndi kosiyana, kotero mkono wa lever (l) nawonso ndi wosiyana. Mu Chithunzi 3, komwe mzere wa ntchito ukupita umagwirizana ndi mzere wozungulira kotero kuti mkono wa lever ndi zero. Mkono wa lever umadziwika pofotokoza mzere kuchokera ku mzere wozungulira kupita ku mzere wa ogwira ntchito. Kumene mzere wa mzere wozungulira uyenera kukhala wolunjika kapena kupanga ngodya ya 90o ndi mzere wa mphamvu.

Yang'anani chithunzi chachiwiri kuti mumvetse bwino equation ya mkono wa lever.

Sin θ = l / r

l = r sin θ

l = mkono wa lever, r = mtunda wa mfundo ya ogwira ntchito ndi mzere wozungulira.

Equation yomwe ili pamwambapa imagwiritsidwa ntchito kuwerengera mkono wa lever. Ngati F ndi yolunjika ku r, ndiye kuti ngodya yopangidwa ndi 90 ^o.

l = r sin 90 ^o = r (1)

l = r

Ngati F ikugwirizana ndi r, ndiye kuti ngodya yopangidwa ndi 0 ^o.

l = r sin 0 ^o = r (0)

l = 0

2.2 Mphamvu ya nthawi (makokedwe)

2.2.1 Kukula kwa mphamvu

Mwa masamu, kukula kwa mphamvu ya mphindi imodzi kumachitika chifukwa cha kuchulukitsa kwa mphamvu (F) ndi mkono wa lever (l).

τ = F l

τ = mphindi ya mphamvu (mita ya Newton), F = mphamvu ( Newton ), l = mkono wa lever (mita)

Equation 2 imagwiritsidwa ntchito kuwerengera kukula kwa mphindi ya mphamvu. Dongosolo lapadziko lonse la torque ndi lofanana ndi ntchito, koma torque si mphamvu, kotero chipangizocho sichiyenera kusinthidwa ndi Joule. Akatswiri a fizikisi nthawi zambiri amagwiritsa ntchito mawu akuti torque, pomwe mainjiniya amagwiritsa ntchito mawu akuti mphindi ya mphamvu.

2.2.2 Malangizo a nthawi ya mphamvu

Nthawi ya mphamvu ndi kuchuluka kwa vekitala chifukwa, kuwonjezera pa kukhala ndi kukula, nthawi ya mphamvu ilinso ndi komwe ikupita. Kulunjika kwa nthawi ya mphamvu kumadziwika mosavuta pogwiritsa ntchito lamulo la dzanja lamanja. Zungulirani zala zinayi za dzanja lanu lamanja, pomwe chala chachikulu cha dzanja lamanja chikuyimiridwa. Kulunjika kwa zala zinayi ndi komwe chinthucho chikuzungulira, pomwe komwe kukuwonetsedwa ndi chala chachikulu ndi komwe kukupita kwa nthawi ya mphamvu.

Ngati njira ya mphamvu ili mmwamba (kumbali ya y-axis) kapena kumanja (kumbali ya x-axis) ndiye kuti nthawi ya mphamvu ndi yabwino. Mosiyana ndi zimenezi, ngati njira ya mphamvu ili pansi (kumbali ya y-axis) kapena kumanzere (kumbali ya –x-axis), nthawi ya mphamvu ndi yoipa. Mwa kuyankhula kwina, ngati njira yozungulira zinthu ili mozungulira wotchi, ndiye kuti nthawi ya mphamvu ndi yoipa. Mosiyana ndi zimenezi, ngati njira yozungulira zinthu ili mozungulira wotchi, ndiye kuti nthawi ya mphamvu ndi yabwino.

2.2.3 Zitsanzo za mavuto a nthawi ya mphamvu

Mavuto a chitsanzo 1.

Chipika chili ndi kutalika kwa mamita 8. Pa mtanda pali mphamvu zitatu, monga momwe zilili pachithunzichi. Kodi mphamvu ya mphindi imodzi yomwe imapangitsa mtanda kuzungulira pakati pake ndi yotani?

yankho;

Pakati pa mtandawo pali pakati. Kutalika kwa mtandawo ndi mamita 8, motero pakati pa mtandawo pali mamita 4 kuchokera kumapeto kwa mtandawo.

Mphamvu 1 = F ₁ l ₁ = (10 N)(4 m) = 40 N m

Mphamvu ya 1 ndi yabwino chifukwa mphamvu ya 1 imapangitsa kuti denga lizizungulira motsatana ndi wotchi.

Mphamvu 2 = F ₂ l ₂ = (10 N)(2 m) = – 20 N m

Mphamvu yachiwiri ndi yoipa chifukwa mphamvu yachiwiri imapangitsa kuti kuwala kuzungulire mozungulira wotchi.

Mphamvu 3 = F ₃ l ₃ = (15 N)(2 m) = – 30 N m

Mphamvu yachiwiri ndi yoipa chifukwa mphamvu yachiwiri imapangitsa kuti kuwala kuzungulire mozungulira wotchi.

Mphamvu yokwanira = 40 N m – 20 N m – 30 N m = – 10 N m

Mphamvu yomwe imabwera chifukwa cha mphamvuyo ndi yoipa, izi zikusonyeza kuti njira yozungulira ya mtandayo ndi yozungulira wotchi.

Mavuto a chitsanzo 2.

F ₁ = 10 N, F ₂ = 15 N, F ₃ = 15 N ndi F ₄ = 10 N, gwiritsani ntchito ndodo ya ABCD monga momwe zasonyezedwera pachithunzichi. Kutalika kwa ndodo ya ABCD ndi mamita 20. Ngati kulemera kwa ndodo sikunyalanyazidwa, mzere wozungulira womwe uli pamalo a D umatsimikiza kukula kwa mphamvu.

yankho;

Funso la vuto ili ndi lakuti kodi mphamvu ya net torque yomwe imapangitsa kuti beam izungulire ndi iti, komwe mzere wozungulira uli pamalo a D.

Mphamvu 1 = F ₁ l ₁ = (10 N)(15 m) = 150 N m

Mphamvu ya 1 ndi yabwino chifukwa mphamvu ya 1 imapangitsa kuti kuwala kuzungulire

mosiyana ndi njira yozungulira wotchi.

Mphamvu 2 = F ₂ l ₂ = (15 N)(5 m) = -75 N m

Mphamvu yachiwiri ndi yoipa chifukwa mphamvu yachiwiri imapangitsa kuti kuwala kuzungulire mbali inayo.

Mphamvu 3 = F ₃ l ₃ = (15 N)(0 m) = 0 N m

Torque 3 ndi zero chifukwa F ₃ imagwirizana ndi mzere wozungulira.

Mphamvu 4 = F ₄ l ₄ = (10 N)(5 m) = 50 N m

Mphamvu yachinayi ndi yabwino chifukwa mphamvu yachinayi imapangitsa kuti kuwala kuzungulire mbali zosiyana mozungulira wotchi.

Mphamvu yokwanira = 150 N m – 75 N m + 50 N m = 125 N m

Mphamvu ya net torque ndi yabwino, motero njira yozungulira ya beam ndi yosiyana ndi njira yozungulira mozungulira.