Zitsanzo za mafunso okhudza Mphamvu ya Ma Mechanical

Zitsanzo 6 za Mafunso a Mphamvu za Makina

Chiphunzitso cha mphamvu ya makina

1. Yang'anani chithunzi chotsatira cha kusamuka kwa boloko! Tiyerekeze kuti g = 10 m/s ² . Ngati coefficient ya kinetic friction pakati pa boloko ndi pansi ndi μ k = 0,5, ndiye kuti mtengo wa kusamuka kwa chinthucho ndi ….

A. 5,00 m

B. 4,25 m

C. 3,00 m

D. 2,50 m

E. 2,00 m

Zokambirana

Amadziwika kuti :

Koyefifiti ya kukangana kwa kinetic ( μ k) = 0,5

Kulemera kwa chipika (m) = 4 kg

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

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

Ngati chipikacho chili pamalo osalala, ndiye kuti mphamvu yachibadwa (N) = kulemera (w) = 40 Newtons.

Liwiro loyambirira (v ₁ ) = 5 m/s

Liwiro lomaliza (v ₂ ) = 0 m/s

Anafunsa : kusamuka kwa chinthu (zinthu)?

Yankho :

Chiphunzitso cha mphamvu ya ntchito ndi makina chimanena kuti ntchito (W) yochitidwa ndi mphamvu yosasinthika ndi yofanana ndi kusintha kwa mphamvu yamakina ya chinthucho kapena mphamvu yomaliza yamakina (EM ₂ ) - mphamvu yoyambirira yamakina (EM ₁ ). Kukangana kwa kinetic ndi mphamvu yosasinthika ndipo mphamvu yokhayo yosasinthika yomwe imagwira ntchito pa block ndi mphamvu ya kukangana kwa kinetic.

W = Δ EM

f _k s = EM ₂ – EM ₁

Ntchito yochitidwa ndi kinetic friction:

W = f _ks = ( μ k )(N)(s) = (0,5)(40)(s) = 20 s

Kusintha kwa mphamvu yamakina:

Δ EM = EM ₂ – EM ₁ = (EK + EP) ₂ – (EK + EP) ₁

Chinthu chimayenda pamalo athyathyathya ndipo sichisintha kutalika ( Δ h = 0) kotero palibe kusintha kwa mphamvu yokoka ( Δ EP = EP ₂ - EP ₁ = 0). Chifukwa chake kusintha kwa mphamvu yamakina kumakhudza kusintha kwa mphamvu ya kinetic.

Δ EM = EK ₂ – EK ₁ = ½ mv ₂ ² – ½ mv ₁ ² = ½ m (v ₂ ² – v ₁ ² )

Δ EM = ½ (4) (0 ² – 5 ² ) = (2) (25) = 50

Kusamutsa kwa block ndi:

W = Δ EM

Masekondi 20 = 50

s = 50 / 20 = mamita 2,5

Yankho lolondola ndi D.

Lamulo losunga mphamvu zamakanika

2. Zinthu A ndi B zili ndi kulemera kofanana. Chinthu A chimagwa kuchokera kutalika kwa mamita h ndipo B chimagwa kuchokera mamita 2. Ngati A igunda pansi ndi liwiro la vm/s, ndiye kuti chinthu B chidzagunda pansi ndi mphamvu ya kinetic ya….

A. 2 mv ²

B. mv ²

C. 3/4 mv ²

D. 1/2 mv ²

E. 1/4 mv ²

Zokambirana

Liwiro lomaliza la chinthu B lomwe limatsika momasuka kuchokera kutalika kwa maola awiri ndi:

v ² = 2 g (maola awiri) = 4 gh

Mphamvu ya kinetic ya chinthu B ndi:

EK _B = ½ mv ² = ½ m (4 gh) = 2 mgh —– Chiyerekezo 1

Mphamvu yoyambirira ya makina ya chinthu B ndi mphamvu yokoka = mg h. Mphamvu yomaliza ya makina ya chinthu B ndi mphamvu ya kinetic = ½ mv ².

Lamulo losunga mphamvu zamakanika :

mgh = ½ mv ².

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

Mphamvu ya kinetic ya chinthu B = 2 mgh = 2(½ mv ² ) = mv ²

Yankho lolondola ndi B.

3. Yang'anani chithunzi chili pansipa! Chinthu chikugwa momasuka kuchokera kutalika kwa mamita 20. Ngati kuthamanga chifukwa cha mphamvu yokoka kuli 10 m/s, ndiye kuti liwiro la chinthucho chikakhala mamita 15 pamwamba pa nthaka ndi….

A. 2 m/s

B. 5 m/s

C. 10 m/s

D. 15 m/s

E. 20 m/s

Zokambirana

Mphamvu yomaliza yamakina = mphamvu yoyambirira yamakina

Mphamvu ya kinetic ya chinthu pa mfundo 2 = kuchepa kwa mphamvu yokoka ndi mamita 5

½ mv ² = mgh

½ v ² = (10)(20-15)

½ v ² = (10)(5)

½ v ² = 50

v ² = (2)(50)

v ² = 100

v = 10 m/s

Yankho lolondola ndi C.

4. Chipika chimagwiridwa pamwamba pa malo opendekeka monga momwe zasonyezedwera pachithunzichi. Chipikacho chikatulutsidwa, chimatsetsereka mopanda kukangana motsatira malo opendekeka. Liwiro la chipikacho likafika pansi pa malo opendekeka ndi…

A. 6 ms^-1

B. 8 ms ^-1

C. 10 ms ^-1

D. 12 ms ^-1

E. 16 ms ^-1

Zokambirana

Mphamvu yoyambirira ya makina = mphamvu yokoka = mgh = m (10)(5) = 50 m

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

Lamulo losunga mphamvu ya makina limati mphamvu yoyamba ya makina = mphamvu yomaliza ya makina.

EM _o = EM _t

50 m = 1/2 mv ²

50 = theka la vesi ²

2 (50) = v ²

100 = v ²

v = 10 m/s

Yankho lolondola ndi C.

5. Chipika chokhala ndi kulemera kwa m kg chimatulutsidwa kuchokera kutalika kwa mamita h pamwamba pa nthaka monga momwe zasonyezedwera pachithunzichi. Chiŵerengero cha mphamvu yothekera (EP) ndi mphamvu ya kinetic (EK) chikakhala pamalo a M ndi….

A. 1: 3

B. 1: 2

C. 2: 1

D. 2: 5

E. 3: 7

Zokambirana

Mphamvu yokoka yomwe imapezeka pa mfundo M:

EP _M = mg (maola 0,3)

Mphamvu ya kinetic pa mfundo M = kuchepetsa mphamvu yokoka ndi h-0,3h = 0,7h

EK _M = EP = mg (maola 0,7)

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

EP _M : EK _M

mg (maola 0,3): mg (maola 0,7)

0,3: 0,7

3: 7

Yankho lolondola ndi E.

6. Yang'anani chithunzi cha chinthu A chikugwa momasuka kuchokera pa mfundo P pansipa!

Ngati EP _Q ndi EK _Q ndi mphamvu zomwe zingatheke komanso mphamvu ya kinetic pa mfundo Q motsatana (g = 10 m/s ² ), ndiye kuti EP _Q : EK _Q ndi….

A. 16: 9

B. 9: 16

C. 3: 2

D. 2: 3

E. 2: 1

Zokambirana

Mphamvu yokoka yomwe ingagwiritsidwe ntchito pa mfundo ya Q:

EP _Q = mgh = (m)(10)(1,8) = 18 m

Mphamvu ya kinetic pa mfundo Q = kuchepetsa mphamvu yokoka ndi 5-1,8 = mamita 3,2

EK _Q = EP = mgh = m (10)(3,2) = 32 m

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

EP _Q : EK _Q

18 m : 32 m

18: 32

9: 16

Gwero la funso:

Mafunso a National Examination Physics a Senior High School/Vocational High School