Zitsanzo 4 za Mafunso a Centripetal Force
1. Chinthu cholemera magalamu 200 chimamangiriridwa ku chingwe chopepuka kenako n’kuzunguliridwa mopingasa ndi liwiro lokhazikika la 5 rad s –1 , monga momwe chithunzi chotsatirachi chikusonyezera. Ngati kutalika kwa chingwe ndi l = 60 cm, ndiye kuti kukula kwa mphamvu yapakati pa chinthucho ndi…
A. 0,3 N
B. 0,6 N
C. 3 N
D. 6 N
E. 30 N
Zokambirana
Amadziwika kuti:
Kulemera kwa chinthu (m) = magalamu 200 = 200/1000 kg = 2/10 kg = 0,2 kg
Liwiro la angular (ω) = ma radians awiri/sekondi
Kutalika kwa chingwe = radius (r) ya njira yozungulira = 60 cm = 60/100 mamita = 0,6 mamita
Funso: Kukula kwa mphamvu yapakati yomwe imagwira ntchito pa chinthu ndi….
Yankho:
Mphamvu yapakati ndi mphamvu yomwe imayambitsa chinthu kuti chiziyenda mofulumira pakati. Fomula ya mphamvu yapakati ndi iyi:
∑ F = ma s
∑ F = mv 2 /r = m ω 2 r
Kufotokozera: ∑ F = mphamvu yapakati, m = kulemera kwa chinthu, v = liwiro la tangential, ω = liwiro la angular, r = radius ya njira yozungulira.
∑ F = m ω 2 r = (0,2)(5) 2 (0,6) = (0,2)(25)(0,6) = 3 Newtons
Yankho lolondola ndi C.
2. Wophunzira akupotoza mwala womangiriridwa kumapeto kwa chingwe. Mwalawo umazunguliridwa mopingasa monga momwe tawonetsera pamwambapa. Ngati liwiro la kuzungulira kwa mwala lawirikiza kawiri, mphamvu yapakati imakhala...
A. Yoyambirira kasanu ndi kamodzi
B. yoyambirira kasanu
C. yoyambirira nthawi 4
D. kawiri kachiwiri
E. Yoyamba kawiri
Zokambirana
Amadziwika kuti:
Unyinji wa mwala = m
Liwiro la mwala = v
Kutalika kwa chingwe = radius = r
Funso: Ngati liwiro lawirikiza kawiri, mphamvu yapakati imakhala...
Yankho:
Ngati liwiro lawirikiza kawiri, ndiye kuti mphamvu yapakati imakhala:
Mphamvu yapakati imakhala yowirikiza kanayi kuposa yoyamba.
Yankho lolondola ndi C.
3. Mzere wokhota pamsewu wathyathyathya wapangidwa kuti udutsemo galimoto pa liwiro lalikulu la 10 ms -1 . Kuchuluka kwa kukangana pakati pa matayala ndi msewu ndi 0,5 ndipo utali wa kupindika kwa msewu ndi R m. Kenako mtengo wa R ndi…. (g = 10 ms -2 )
A. mamita 7,5
B. mamita 8,0
C. 10 mamita
D. 15 mamita
E. mamita 20
Zokambirana
Amadziwika kuti:
Liwiro (v) = 10 m/s
Kuchuluka kwa kukangana pakati pa tayala ndi msewu (μ s ) = 0,5
Kuthamanga chifukwa cha mphamvu yokoka (g) = 10 m/s 2
Funso: Ma radius a kupindika kwa msewu (R mita)
Yankho:
Mphamvu yokhayo yopingasa yomwe imagwira ntchito pa galimoto ikatembenuka ndi static friction . Fomula ya static friction ndi iyi:
4. Galimoto ikuyendetsa mokhota pamsewu pamalo M monga momwe chithunzi chili pansipa chikusonyezera.
Kuchuluka kwa kukangana kosasinthasintha pakati pa mawilo ndi msewu ndi 0,4 (kuthamanga kwa mphamvu yokoka 10 m/s -2 ). Kuti galimoto isachoke panjira, liwiro lalikulu lomwe liloledwa ndi…
A. √10 ms-1
B. 2 √ 10 ms -1
C. 4 √ 10 ms -1
D. 5 √ 10 ms -1
E. 6 √ 10 ms -1
Zokambirana
Amadziwika kuti:
Chokwanira cha kusinthasintha kosasunthika (μ s ) = 0,4
Kuthamanga chifukwa cha mphamvu yokoka (g) = 10 m/s 2
Ulalo wozungulira (R) = mamita 40
Anafunsa: liwiro lalikulu (v)
Yankho:
Lamulo lachiwiri la Newton la kuyenda mozungulira mofanana
Zambiri:
ΣF = mphamvu yapakati = mphamvu yochokera = mphamvu yonse, m = kulemera kwa chinthu, a s = kuthamanga kwapakati, v = liwiro lolunjika, R = utali wozungulira wa kupindika
Mphamvu yapakati
Mphamvu yapakati ndi mphamvu yochokera pakati pa njira yozungulira. Galimoto ikayenda mozungulira, mphamvu yokhayo yolunjika pakati ndi kukangana kosasinthasintha, kotero kukangana kosasinthasintha ndi mphamvu yapakati.
Fomula ya mphamvu yokangana yosasinthasintha:
Zambiri:
μ s = coefficient of static friction, w = kulemera kwa chinthu, m = kulemera kwa chinthu, g = kuthamanga chifukwa cha mphamvu yokoka.
Werengani liwiro lalikulu (v):
Yankho lolondola ndi C.
Gwero la funso:
Mafunso a National Examination Physics a Senior High School/Vocational High School
