Zitsanzo za mafunso okhudza ntchito ndi mphamvu yokoka

Zitsanzo 4 za ntchito ndi mphamvu yokoka

1. Chinthu cholemera makilogalamu 1 chimagwa momasuka kuchokera kutalika kwa mamita 10 mpaka chikafika pansi. Dziwani izi:
(a) Ntchito yochitidwa ndi mphamvu yokoka pa chinthucho
(b) Zosintha mphamvu zomwe zingatheke mphamvu yokoka
Kuthamanga chifukwa cha mphamvu yokoka (g) = 10 m/s²
Zokambirana
Ndizodziwika kuti :
Kulemera kwa chinthu (m) = 1 kg
Kutalika (h) = mamita 10
Kuthamanga chifukwa cha mphamvu yokoka (g) = 10 m/s²
Yankho:
(a) Ntchito yochitidwa ndi mphamvu yokoka
Chinthu chikagwa momasuka, njira yoyendera ya chinthucho imakhala pansi ndipo njira ya mphamvu yokoka yomwe ikugwira ntchito pa chinthucho (kulemera kwa chinthucho) nayonso imakhala pansi. Chifukwa chakuti zili mbali imodzi, mphamvu yokoka imagwirizana kapena kupanga ngodya ya 0.^o ndi malangizo a kayendetsedwe ka chinthucho. Cos 0 = 1 ndipo nambala iliyonse yochulukitsidwa ndi 1 ndi yofanana ndi nambala imeneyo, kotero cos 0 sikuyenera kuphatikizidwa mu fomula yogwirira ntchito.
Fomula yogwirira ntchito ndi W = F s, pomwe W = ntchito, F = mphamvu ndi s = kusamuka. Ngati yasinthidwa kuti igwirizane ndi vutoli, fomula yogwirira ntchito imasintha kukhala W = wh = mgh, pomwe W = ntchito, w = mphamvu yokoka, h = kusintha kwa kutalika kwa chinthucho, m = kulemera kwa chinthucho, g = kuthamanga chifukwa cha mphamvu yokoka.
Kotero ntchito yochitidwa ndi mphamvu yokoka ndi iyi:
W = wh = mgh = (1)(10)(10) = 100 Joules

(b) Kusintha kwa mphamvu yokoka
Pa kutalika kwa mamita 10 kuchokera pansi, mphamvu yokoka ya chinthucho ndi ma Joules 100. Pamene chikuyenda pansi, kutalika kwa chinthucho kumachepa, motero chimachepetsa mphamvu yake yokoka. Chikafika pamtunda, pomwe kutalika kwa chinthucho ndi zero, mphamvu yake yokoka ndi zero. Chifukwa chake, mphamvu yokoka ya chinthucho imachepa ndi ma Joules 100.

2. Chinthu cholemera ma Newton 10 chili pa malo osalala okhala ndi ngodya ya 30°.^oKutalika kwa hypotenuse ndi mamita awiri. Ntchito yokoka yomwe imachitidwa ndi mphamvu yokoka pa chinthucho pamene chikutsetsereka motsatira hypotenuse ndi…
Zokambirana
Ndizodziwika kuti :
Mphamvu yokoka (w) = 10 Newton
w_x = uchimo titi = (10)(chimo 30^o) = (10)(0,5) = 5 Newton
Kutalika kwa hypotenuse (s) = mamita awiri
Kuthamanga chifukwa cha mphamvu yokoka (g) = 10 m/s²
Anafunsa : ntchito yochitidwa ndi mphamvu yokoka
Yankhani :
Vutoli lingathe kuthetsedwa pogwiritsa ntchito njira ziwiri.
Njira yoyamba :
Fomula yogwirira ntchito ndi W = F s. Ngati yasinthidwa kuti igwirizane ndi vutoli, fomula yogwirira ntchito imasintha kukhala W = w_x s. Kotero ntchito yochitidwa ndi mphamvu yokoka ndi W = w_x s = (5)(2) = 10 Ma Joules.
Njira yachiwiri :
Ntchito yochitidwa ndi mphamvu yokoka, monga mphamvu yokoka, siidalira njira yomwe chinthucho chimatenga koma imadalira kusintha kwa kutalika. Chifukwa chake, kuti muwerenge ntchito yochitidwa ndi mphamvu yokoka, choyamba werengani kutalika kwa chinthucho.
Tchimo 30^o = mbali yoyimirira / hypotenuse
0,5 = mbali yopingasa / 2
Mbali yoyima = (0,5)(2)
Mbali yoyima = mita imodzi
Kutalika kwa chinthucho ndi mita imodzi.
Ntchito yochitidwa ndi mphamvu yokoka pamene chinthucho chikutsika pansi ndi W = wh = (10)(1) = 10 Joules.

3. Mphamvu zokwana ma Joules 5000 zimagwiritsidwa ntchito kunyamula chinthu cholemera makilogalamu 50. Chinthucho chidzakwera kufika kutalika kwa… g = 10 m/s²
A. 5 m
B. 10 m
C. 12 m
D. 15 m
E. 20 m
Kukambirana:
Ndizodziwika kuti :
Mphamvu yokoka ya EP = 5000 Joules, m = 50 kg, g = 10 m/s².
Anafunsa :
h ?
Yankhani :
EP = mgh
5000 = (50)(10)(h)
5000 = maola 500
h = 5000 / 500 = mamita 10
Yankho lolondola ndi B.

4. Chinthu cholemera makilogalamu awiri chili pamtunda wa mamita asanu kuchokera pansi. Kuthamanga chifukwa cha mphamvu yokoka = 10 m/s². Khama lofunika kuti munthu anyamule chinthucho mpaka kutalika kwa mamita 15 kuchokera pamwamba pa dziko lapansi ndi…
A. 100 Joule
B. 200 Joule
C. 300 Joule
D. 400 Joule
E. 500 Joule
Kukambirana:
Ndizodziwika kuti :
m = 2 kg, h₁ = mamita 5, h₂ = mamita 15, g = 10 m/s²
Anafunsa :
W ?
Yankhani :
Ntchito (W) = kusintha kwa mphamvu yokoka (EP)₂ -EP₁).
W = EP₂ -EP₁
W = mgh₂ – mgh₁
W = mg (h₂ - h₁)
W = (2)(10)(15-5) = (2)(10)(10) = 200 Joules.
Yankho lolondola ndi B.