Zitsanzo 4 za Mafunso Okhudza Kusokonezeka Maganizo
1. Mpira wolemera makilogalamu 0,5 umagwa momasuka kuchokera kutalika kwa h 1 = 7,2 m kuchokera pansi ndipo umadumpha mpaka kutalika kwa h 2 = 3,2 m. Ngati kuthamanga chifukwa cha mphamvu yokoka kuli 10 ms -2 , mphamvu yomwe imagwira ntchito pa mpira ndi...
A. 2,0 Ns
B. 3,0 Ns
C. 10 Ns
D. 40 Ns
E. 80 Ns
Zokambirana
Amadziwika kuti :
Kulemera kwa mpira (m) = 0,5 kg
Kutalika kwa mpira wogwa momasuka (h 1 ) = mamita 7,2
Kutalika kwa mpira wodumphadumpha (h 2 ) = mamita 3,2
Kuthamanga kwa mphamvu yokoka kwa dziko lapansi (g) = 10 m/s 2
Anafunsa : Kutengeka mtima pa mpira
Yankho :
Liwiro la mpira lisanafike nthawi yogunda (v)o)
Werengerani liwiro la mpira musanayambe kugwedezeka pogwiritsa ntchito njira yolowera mu free fall. Popeza kutalika (h) = 7,2 metres, kuthamanga chifukwa cha mphamvu yokoka (g) = 10 m/s 2 ndi liwiro lomaliza musanayambe kugwedezeka pansi, gwiritsani ntchito njira iyi v 2 = 2 gh
v o 2 = 2(10)(7,2) = 144
v o = 2(10)(7,2) = 12 m/s
Liwiro la mpira usanagwe (vo o ) ndi -12 m/s. Chizindikiro chotsutsa chimangosonyeza komwe mpirawo ukupita.
Liwiro la mpira nthawi yomweyo pambuyo pa kugundana (v)t)
Werengerani liwiro la mpira nthawi yomweyo mutagundana pogwiritsa ntchito njira yoyendetsera molunjika mmwamba. Popeza kutalika (h) = 3,2 metres, kuthamanga kwa mphamvu yokoka (g) = -10 m/s 2 , liwiro lomaliza pa kutalika kwakukulu (v t 2 ) = 0 ndipo liwiro loyambirira nthawi yomweyo mutagunda pansi limafunsidwa, chifukwa chake gwiritsani ntchito njira iyi v t 2 = v o 2 + 2 gh
v t 2 = v o 2 + 2 gh
0 = vo 2 + 2 (-10)(3,2)
vesi 2 = 64
v o = √64 = 8 m/s
Liwiro la mpira pambuyo pa kugundana (v t ) ndi 8 m/s
Kuchita zinthu mopupuluma pa mpira (I)
Impulse imawerengedwa pogwiritsa ntchito njira ya impulse-momentum theorem.
Kusakhazikika (I) = kusintha kwa mphamvu (Δp)
I = m (v t – vo o ) = (0,5)(8-(-12)) = (0,5)(8 + 12) = 0,5(20) = masekondi 10 a Newton
Yankho lolondola ndi C.
2. Mpira wa ping pong wokhala ndi kulemera kwa magalamu 5 umagwa momasuka kuchokera kutalika kwinakwake (g = 10 ms -2 ). Ukagunda pansi, liwiro la mpirawo ndi 6 ms -1 ndipo nthawi yomweyo ukagunda pansi, mpirawo umadumphira mmwamba ndi liwiro la 4 ms -1 . Kukula kwa mphamvu yomwe imagwira ntchito pa mpirawo ndi...
A. 0,50 Ns
B. 0,25 Ns
C. 0,10 Ns
D. 0,05 Ns
E. 0,01 Ns
Zokambirana
Amadziwika kuti :
Kulemera kwa mpira (m) = magalamu 5 = 0,005 kg
Liwiro la mpira lisanafike pansi (v o ) = -6 m/s
Liwiro la mpira nthawi yomweyo ukangogunda pansi (v t ) = 4 m/s
Liwiro labwino ndi loipa limatanthauza kuti komwe mpira uli kapena komwe mpirawo ukuyenda usanagunde ndi kosiyana ndi komwe mpirawo ukuyenda utatha kugundana.
Anafunsa : Impulse (I)
Yankho :
Chiphunzitso cha impulse-momentum chimanena kuti impulse (I) ndi yofanana ndi kusintha kwa mphamvu (Δp).
I = Δp = mv t – mv o = m (v t – v o )
I = (0,005)(4 – (-6)) = (0,005)(4 + 6) = (0,005)(10) = 0,05 Newton second
Yankho lolondola ndi D.
3. Mpira wa magalamu 20 umaponyedwa ndi liwiro v 1 = 4 ms -1 kumanzere. Pambuyo pogunda khoma, mpirawo umadumphadumpha ndi liwiro v 2 = 2 ms -1 kumanja. Mphamvu yomwe imabwera chifukwa cha izi ndi….
A. 0,24 Ns
B. 0,12 Ns
C. 0,08 Ns
D. 0,06 Ns
E. 0,04 Ns
Zokambirana
Amadziwika kuti:
Kulemera kwa mpira (m) = magalamu 20 = 0,020 kg
Liwiro la mpira usanagunde (vo o ) = -4 m/s (kumanzere)
Liwiro la mpira pambuyo pa kugundana (v t ) = +2 m/s (kumanja)
v o imapatsidwa chizindikiro chotsutsa kuti isiyanitse njira yake ndi v t.
Anafunsa: Kusakhazikika
Yankho:
Kusakhazikika (I) = kusintha kwa mphamvu (Δp) = mv t – mv o
Kukakamiza (I) = m (v t – vo o ) = 0,02 (2 – (-4))
Kukakamiza (I) = 0,02 (2 + 4) = 0,02 (6)
Mphamvu (I) = masekondi 0,12 a Newton.
Yankho lolondola ndi B.
4. Mpira wa tenisi wa magalamu 100 umagwetsedwa pansi kuchokera kutalika kwa masentimita 20 popanda liwiro loyambirira. Pambuyo pogunda pansi, mpira umadumphadumpha ndi liwiro la 1 ms -1 ndi (g = 10 ms -2 ). Kusintha kwa mphamvu ya mpira ndi...
A. 0,1 Ns
B. 0,3 Ns
C. 0,5 Ns
D. 0,8 Ns
E. 0,9 Ns
Zokambirana
Ndizodziwika kuti :
Kulemera kwa mpira (m) = magalamu 100 = 0,1 kg
Kutalika (h) = 20 cm = 0,2 mamita
Kuthamanga chifukwa cha mphamvu yokoka (g) = 10 m/s2
Liwiro la mpira nthawi yomweyo ukangogunda pansi (v)t) = 1 m/s
Anafunsa : kusintha kwa mphamvu ya mpira
Yankhani :
Liwiro la mpira usanagwe (v)o)
Werengerani liwiro la mpira musanagunde pogwiritsa ntchito njira yolowera mu free fall. Popeza kutalika kwa free fall ya mpira (h) = 0,2 metres, kuthamanga chifukwa cha mphamvu yokoka (g) = 10 m/s2 ndipo anafunsa liwiro la mpirawo ukagunda pansi, chifukwa chake njirayo imagwiritsidwa ntchito v2 = 2 gh
v2 = 2 (10)(0,2) = 4
v= √4 = -2 m/s
Chimapatsidwa chizindikiro chotsutsa chifukwa chakuti komwe mpira ukuyenda usanagunde pansi kumakhala kosiyana ndi komwe mpira ukuyenda utatha kugundana ndi pansi.
Kusintha kwa mphamvu ya mpira (Δp)
Δp = mvt – mvo = m (vt -vo)
Δp = (0,1)(1 – (-2)) = (0,1)(1 + 2) = (0,1)(3) = 0,3 Sekondi ya Newton
Yankho lolondola ndi B.
Gwero la funso:
Mafunso a National Examination Physics a Senior High School/Vocational High School
