Mphamvu ya makina - mavuto ndi mayankho

Mfundo ya mphamvu ya ntchito ndi makina

1. Chiŵerengero cha kukangana kwa kinetic pakati pa block ndi floor (μ _{k ) ndi 0.5. Kodi}kusamuka kwa chinthu (zinthu) ndi kotani ? Kuthamanga chifukwa cha mphamvu yokoka ndi 10 m/s ².

Zodziwika: Mphamvu ya makina - mavuto ndi mayankho 1

Chiŵerengero cha kupsinjika kwa kinetic (μ _k ) = 0.5

Kulemera kwa chipika (m) = 4 kg

Kuthamanga chifukwa cha mphamvu yokoka (g) ndi 10 m/s ²

Kulemera kwa chipika (w) = mg = (4)(10) = 40 Newtons

Ngati chipika chili pa ndege yopingasa ndiye kuti mphamvu yachibadwa (N) = kulemera (w) = 40 Newtons.

Liwiro loyambirira (v ₁ ) = 5 m/s

Liwiro lomaliza (v ₂ ) = 0 m/s

Kufunidwa: kusamutsidwa kwa chinthu (d)?

Yankho:

Mfundo ya mphamvu ya ntchito ndi makina imati ntchito (W) yochitidwa ndi mphamvu yosasintha zinthu ndi yofanana ndi kusintha kwa mphamvu ya makina ya chinthu. Kusintha kwa mphamvu ya makina = mphamvu yomaliza ya makina - mphamvu yoyambirira ya makina.

Mphamvu ya kinetic friction ndi imodzi mwa mphamvu zosasunga chilengedwe ndipo ndi mphamvu yokhayo yosasunga chilengedwe yomwe imagwira ntchito pa block.

W = ΔME

f _k d = INE ₂ – INE ₁

Ntchito yochitidwa ndi mphamvu ya kinetic friction:

W = f _k d = (μ _k )(N)(d) = (0.5)(40)(d) = 20 d

Kusintha kwa mphamvu ya makina:

ΔME = ME ₂ – ME ₁ = (KE + PE) ₂ – (KE + PE) ₁

Chinthu chimayenda mozungulira malo opingasa ndipo palibe kusintha kwa kutalika (Δh = 0) kotero palibe kusintha kwa mphamvu yokoka (ΔPE = PE ₂ - PE ₁ = 0). Chifukwa chake kusintha kwa mphamvu yamakina kumakhudza kusintha kwa mphamvu ya kinetic.

ΔME = KE ₂ – KE ₁ = ½ mv ₂² – ½ mv ₁² = ½ m (v ₂² – v ₁² )

Δ M E = ½ (4) (0 ² - 5 ² ) = (2) (25) = 50

Kusamutsa kwa chipika:

W = ΔME

Masekondi 20 = 50

s = 50 / 20

s = mamita 2.5

Mfundo yosungira mphamvu zamakanika

2. Chinthu A ndi chinthu B zili ndi kulemera kofanana. Chinthu A chimagwa kuchokera kutalika kwa mamita h ndipo chinthu B chimagwa kuchokera kutalika kwa mamita 2. Ngati chinthu A chigunda pansi pa vm/s, ndiye mphamvu ya kinetic ya chinthu B ndi yotani ikagunda pansi?

Yankho:

Liwiro lomaliza la chinthu B pamene chikugwa momasuka kuchokera kutalika kwa maola awiri:

v ² = 2 g (maola awiri) = 4 gh

Mphamvu ya kinetic ya chinthu B:

KUYAMBIRA _B = ½ mv ² = ½ m (4 gh) = 2 mgh —– equation 1

Mphamvu yoyambirira ya makina ya chinthu B = mphamvu yokoka = mg h.

Mphamvu yomaliza ya makina ya chinthu B = mphamvu ya kinetic = ½ mv ².

Mfundo yosungira mphamvu zamakanika:

mgh = ½ mv ²

Chifukwa mgh = ½ mv ² ndiye kuti tikhoza kusintha mgh mu equation 1 ndi ½ mv ².

Mphamvu ya kayendedwe ka chinthu B = 2 mph = 2(½ mv ² ) = mv ²

3. Kugwa popanda chinthu kuchokera kutalika kwa mamita 20. Kuthamanga chifukwa cha mphamvu yokoka ndi 10 m/s. Kodi liwiro la chinthu chomwe chili mamita 15 pamwamba pa nthaka ndi lotani?

Yankho: Mphamvu ya makina - mavuto ndi mayankho 2

Mphamvu yomaliza yamakina = mphamvu yoyambirira yamakina

Mphamvu ya kinetic pa mfundo 2 = kusintha kwa mphamvu yokoka mpaka mamita 5.

Mphamvu ya makina - mavuto ndi mayankho 3

4. Chipika chimatulutsidwa kuchokera pamwamba pa malo otsetsereka bwino. Kodi liwiro la chipikacho limakhala lotani chikagunda pansi?

Yankho:

Mphamvu yoyambirira ya makina = mphamvu yokoka = mgh = m (10)(5) = mamita 50 Mphamvu ya makina - mavuto ndi mayankho 4

Mphamvu yomaliza ya makina = mphamvu ya kinetic = 1/2 mv ²

Mfundo yosungira mphamvu ya makina, imati mphamvu yoyamba ya makina = mphamvu yomaliza ya makina.

INE _o = INE _t

50 m = 1/2 mv ²

50 = theka la vesi ²

2 (50) = v ²

100 = v ²

v = 10 m/s

Chipika chokhala ndi kulemera kwa m-kg chotulutsidwa kuchokera kutalika kwa mamita h pamwamba pa nthaka, monga momwe chithunzi chili pansipa chikusonyezera. Dziwani chiŵerengero cha mphamvu yomwe ingakhalepo ku mphamvu ya kinetic (KE) pamalo a M.

Yankho:

Mphamvu yokoka yomwe imapezeka pa mfundo M: Mphamvu ya makina - mavuto ndi mayankho 5

PE _M = mg (maola 0.3)

Mphamvu ya kinetic pa mfundo m = kusintha kwa mphamvu yokoka mpaka h-0.3h = 0.7h

KE _M = PE = mg (0.7 h)

Chiŵerengero cha mphamvu yokoka ndi mphamvu ya kinetic pa mfundo M:

PE _M : KE _M

mg (maola 0.3): mg (maola 0.7)

0.3: 0.7

3: 7

6. Ngati PE _Q ndi KE _Q zili ndi mphamvu yothekera komanso mphamvu ya kinetic pamalo a Q (g = 10 m/s ² ), ndiye kuti PE _Q : KE _Q =…

Yankho:

Mphamvu yokoka yomwe imapezeka pa mfundo ya Q: Mphamvu ya makina - mavuto ndi mayankho 6

PE _Q = mgh = (m)(10)(1.8) = mamita 18

Mphamvu ya kinetic pa mfundo Q = kusintha kwa mphamvu yokoka mpaka 5-1.8 = mamita 3.2

KUTI _Q = PE = mgh = m (10)(3.2) = 32 m

Chiŵerengero cha mphamvu yokoka ndi mphamvu ya kinetic pa mfundo Q:

PE _Q : KE _Q

18 m : 32 m

18: 32

9: 16

Kodi mphamvu ya makina ndi chiyani? yankhoMphamvu ya makina ndi kuchuluka kwa mphamvu zomwe zingatheke komanso mphamvu ya kinetic mu dongosolo. Imayimira kuchuluka kwa mphamvu zonse zokhudzana ndi kuyenda ndi malo a chinthu.
Kodi mphamvu ya kinetic imasiyana bwanji ndi mphamvu yomwe ingakhalepo? yankhoMphamvu ya kinetic ndi mphamvu yoyenda, pomwe mphamvu yothekera ndi mphamvu yosungidwa chifukwa cha malo kapena kapangidwe ka chinthu. Mwachitsanzo, galimoto yoyenda imakhala ndi mphamvu yothekera, pomwe kasupe wotambasuka kapena chinthu chomwe chili pamtunda mu gawo la mphamvu yokoka chimakhala ndi mphamvu yothekera.
Kodi mphamvu ya makina nthawi zonse imasungidwa? yankho: Mu dongosolo labwino, lotsekedwa lopanda mphamvu zakunja, mphamvu yamakina imasungidwa. Komabe, m'mikhalidwe yeniyeni, mitundu ina ya mphamvu monga kutentha kapena mphamvu yamawu imatha kugwira ntchito chifukwa cha kukangana kapena mphamvu zina zosasintha, zomwe zimapangitsa kuti mphamvu yonse yamakina ichepe.
Kodi kusunga mphamvu zamakanika kumathandiza bwanji kuthetsa mavuto? yankho: Pamene mphamvu ya makina imasungidwa mu dongosolo (palibe mphamvu zosasintha monga kukangana), mphamvu yonse pachiyambi imakhala yofanana ndi mphamvu yonse kumapeto. Mfundo imeneyi imatithandiza kulumikiza mphamvu zomwe zingatheke komanso mphamvu zomwe zimayenda nthawi zosiyanasiyana, zomwe zimapangitsa kuti njira yothetsera mavuto ikhale yosavuta.
Kodi chimachitika ndi chiyani ndi mphamvu ya makina ya mpira ikaponyedwa mmwamba n’kuima kwakanthawi isanatsike? yankho: Pamene mpira ukukwera, mphamvu yake ya kayendedwe ka thupi imachepa pamene mphamvu yake yowonjezera imawonjezeka. Pamwamba, mphamvu yake yonse ya makina ndi mphamvu yowonjezera. Pamene ukutsika, njirayi imabwerera m'mbuyo. Muzochitika zabwino popanda kukana mpweya, mphamvu yonse ya makina ya mpira imakhalabe yokhazikika paulendo wake wonse.
Kodi chinthu chingakhale ndi mphamvu ya kinetic komanso ya potential nthawi imodzi? yankhoInde, chinthu chingakhale ndi mitundu yonse iwiri ya mphamvu nthawi imodzi. Mwachitsanzo, pendulum yomwe ili pakati pa kugwedezeka kwake imakhala ndi mphamvu ya kinetic chifukwa cha kuyenda kwake komanso mphamvu zomwe zingatheke chifukwa cha kutalika kwake pamwamba pa malo ake otsika kwambiri.
Kodi roller coaster imasonyeza bwanji kuti mphamvu ya makina imasungidwa? yankho: Chiwombankhanga chozungulira chimayamba ndi mphamvu yomwe ingathe kufika pamalo ake apamwamba kwambiri. Pamene chikutsika, mphamvu yomwe ingathe kufikayi imasanduka mphamvu ya kinetic, zomwe zimapangitsa kuti chiwombankhanga chizithamanga. Pamene chikukweranso, mphamvu ya kinetic imachepa pamene mphamvu yomwe ingathe kufika ikuwonjezeka. Ponyalanyaza kukangana ndi kukana mpweya, mphamvu yonse ya makina imakhalabe yofanana.
Ndi zinthu ziti zomwe zingayambitse kutayika kwa mphamvu ya makina m'machitidwe enieni? yankho: Kukangana, kukana mpweya, ndi kupanga mawu ndi zina mwa zinthu zomwe zingayambitse kutayika kwa mphamvu m'machitidwe enieni. Mphamvuyo siiwonongeka (chifukwa cha lamulo losunga mphamvu) koma imasinthidwa kukhala mitundu ina monga kutentha kapena phokoso.
Kodi pali ubale wotani pakati pa ntchito ndi mphamvu ya makina? yankho: Ntchito yochitidwa pa dongosolo ndi mphamvu zakunja ingayambitse kusintha kwa mphamvu ya makina a dongosolo. M'masamu, ntchito ndi yofanana ndi kusintha kwa mphamvu ya makina.
Ngati mphamvu yokoka ikugwirizana ndi mfundo yofotokozera, kodi tingayeze bwanji kusintha kwake nthawi zonse? Yankho : Ngakhale kuti phindu lenileni la mphamvu yokoka limadalira kusankha mfundo yofotokozera, kusintha kwa mphamvu yokoka (monga pamene chinthu chakwezedwa kapena kutsika) kumakhala kofanana mosasamala kanthu za mfundo yofotokozera. Chifukwa chake, nthawi zambiri timayang'ana kwambiri kusintha kwa mphamvu yokoka m'malo mwa mfundo zenizeni.