Zitsanzo za mafunso okhudza Mphamvu ya Ma Mechanical

Zitsanzo 6 za Mafunso a Mphamvu za Makina

Chiphunzitso cha mphamvu ya makina

1. Samalani ndi chithunzicho kusamutsidwa bloki motere! Tiyerekeze kuti g = 10 m/s²Ngati coefficient ya kinetic friction pakati pa block ndi pansi μk = 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

Ndizodziwika kuti :

Koyenenti ya kukangana kwa kinetic (μk) = 0,5

Kulemera kwa chipika (m) = 4 kg

Kuthamanga chifukwa cha mphamvu yokoka (g) = 10 m/s²

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)?

Yankhani :

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

W= ΔEM

f_k s = EM₂ – EM₁

Ntchito yochitidwa ndi kinetic friction:

W = f_k s = (μk)(N)(s) = (0,5)(40)(s) = masekondi 20

Kusintha kwa mphamvu yamakina:

ΔEM = EM₂ – EM₁ = (EK + EP)₂ – (EK + EP)₁

Zinthu zimasuntha pamalo athyathyathya ndipo sizisintha kutalika (Δh = 0) kotero palibe kusintha kwa mphamvu yokoka (ΔEP = EP₂ -EP₁ = 0). Choncho kusintha kwa mphamvu ya makina kumakhudza kusintha kwa mphamvu ya kinetic kokha.

ΔEM = EK₂ – EK₁ = ½ mv₂² – ½ mv₁² = ½ m (v)₂² -v₁²)

ΔEM = ½ (4)(0² - 5²) = (2)(25) = 50

Kusamutsa kwa block ndi:

W= ΔEM

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 mv²

B. mv²

C. 3/4 mv²

D. 1/2 mv²

E. 1/4 mv²

Zokambirana

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

v² = 2 g (maola awiri) = 4 gh

Mphamvu ya kinetic ya chinthu B ndi:

EK_B = ½ mv² = 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 mv².

Lamulo losunga mphamvu zamakanika :

mgh = ½ mv².

Chifukwa mgh = ½ mv² kenako titha kusintha mgh mu equation 1 ndi ½ mv².

Mphamvu ya kinetic ya chinthu B = 2 mgh = 2(½ mv)²) = mv²

Yankho lolondola ndi B.

3. Yang'anani chithunzi chili pansipa! Chinthu chimagwa 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 mv² = mgh

½ v² = (10)(20-15)

½ v² = (10)(5)

½ v² = 50

v² = (2)(50)

v² = 100

v = 10 m/s

Yankho lolondola ndi C.

4. Chipika chimagwiridwa pamwamba pa malo opendekera monga momwe chithunzichi chikusonyezera. Chipikacho chikatulutsidwa, chimatsetsereka mopanda kukangana motsatira malo opendekera. Liwiro la chipikacho likafika pansi pa malo opendekera 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 yamakina = mphamvu ya kinetic = 1/2 mv²

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

EM_o = EM_t

50 m = 1/2 mv²

50 = 1/2 v²

2 (50) = v²

100 = v²

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 chilichonse ndi mphamvu yothekera komanso mphamvu ya kinetic pamalo Q (g = 10 m/s²), kenako 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