Lamulo Lachiwiri la Newton ndi limodzi mwa mfundo zazikulu mu fizikisi zomwe zimalamulira ubale pakati pa mphamvu, kulemera, ndi kuthamanga. Lamuloli limati kuthamanga kwa chinthu kumafanana ndi mphamvu yeniyeni yomwe ikugwira ntchito pa icho ndipo kumafanana ndi kulemera kwake. Mwa masamu, Lamulo Lachiwiri la Newton limanenedwa motere:
\[ F = ma \]
Kumene:
– \( F \) ndi mphamvu ya ukonde yomwe imagwira ntchito pa chinthucho (mu Newtons, N).
– \( m \) ndi kulemera kwa chinthucho (mu makilogalamu, kg).
– \( a \) ndi kufulumira kwa chinthu (mu mamita pa sekondi imodzi, \( m/s^2 \)).
M'nkhaniyi, tikambirana zitsanzo zina za Lamulo Lachiwiri la Newton kuti timvetse momwe limagwiritsidwira ntchito pazochitika zosiyanasiyana.
Chitsanzo Funso 1: Limbikitsani Galimoto Yothamanga
Funso:
Galimoto yolemera makilogalamu 1000 imathamanga kuchoka pamalo opumula kupita pa liwiro la 20 m/s mu masekondi 5. Werengani mphamvu yofunikira kuti mukwaniritse kuthamanga kumeneku.
Yankho:
Choyamba, tifunika kuwerengera kufulumira kwa galimoto. Kuthamanga (\( a \)) kungawerengedwe pogwiritsa ntchito fomula iyi:
\[ a = \frac{\Delta v}{\Delta t} \]
Kumene:
– \(\Delta v\) ndi kusintha kwa liwiro.
– \(\Delta t\) ndi kusintha kwa nthawi.
M'malo mwa mfundo zodziwika bwino:
\[ a = \frac{20 \, \text{m/s} – 0 \, \text{m/s}}{5 \, \text{seconds}} \]
\[ a = \frac{20 \, \text{m/s}}{5 \, \text{seconds}} \]
\[ a = 4 \, \text{m/s}^2 \]
Tsopano, tikhoza kuwerengera mphamvu yofunikira pogwiritsa ntchito lamulo lachiwiri la Newton:
\[ F = ma \]
\[ F = (1000 \, \text{kg})(4 \, \text{m/s}^2) \]
\[ F = 4000 \, \malemba{N} \]
Kotero, mphamvu yofunikira kuti galimoto iyende mofulumira ndi 4000 N.
Chitsanzo Funso 2: Mphamvu Yokangana pa Bokosi
Funso:
Bokosi lolemera makilogalamu 50 limakankhidwira pamalo osasunthika ndi mphamvu ya 300 N. Ngati mphamvu yokangana pakati pa bokosi ndi pamwamba ndi 100 N, werengani kuthamanga kwa bokosilo.
Yankho:
Choyamba, timawerengera mphamvu ya neti yomwe ikugwira ntchito pa bokosi. Mphamvu ya neti (\( F_{\text{net}} \)) ndi mphamvu yonse yomwe ikugwira ntchito pa chinthu mutaganizira mphamvu zonse zomwe zikugwira ntchito pa icho, kuphatikizapo kukangana.
\[ F_{\text{net}} = F_{\text{push}} – F_{\text{friction}} \]
\[ F_{\text{net}} = 300 \, \text{N} – 100 \, \text{N} \]
\[ F_{\text{net}} = 200 \, \text{N} \]
Tsopano, tikhoza kuwerengera kufulumira kwa bokosi pogwiritsa ntchito Lamulo Lachiwiri la Newton:
\[ F_{\text{net}} = ma \]
\[ 200 \, \malemba{N} = (50 \, \malemba{kg})a \]
\[ a = \frac{200 \, \text{N}}{50 \, \text{kg}} \]
\[ a = 4 \, \text{m/s}^2 \]
Kotero, kuthamanga kwa bokosi ndi 4 m/s².
Chitsanzo Funso 3: Kuwerengera Mphamvu Yofunika Ponyamula Katundu
Funso:
Kreni imanyamula katundu wolemera makilogalamu 200 kupita mmwamba ndi liwiro la 1,5 m/s². Werengani mphamvu yomwe kreni imafunika kuti inyamule katunduyo.
Yankho:
Choyamba, tifunika kuwerengera mphamvu yokoka yomwe imagwira ntchito pa katundu. Mphamvu yokoka (\( F_g \)) ikhoza kuwerengedwa pogwiritsa ntchito fomula iyi:
\[ F_g = mg \]
Kumene:
– \( g \) ndi kufulumira chifukwa cha mphamvu yokoka (\( 9,8 \, \text{m/s}^2 \)).
M'malo mwa mfundo zodziwika bwino:
\[ F_g = (200 \, \text{kg})(9,8 \, \text{m/s}^2) \]
\[ F_g = 1960 \, \malemba{N} \]
Tsopano, tikuwerengera mphamvu yonse (\( F \)) yomwe crane imafunika kuti inyamule katundu poganizira kuthamangitsidwa kwina:
\[ F = ma + F_g \]
\[ F = (200 \, \text{kg})(1,5 \, \text{m/s}^2) + 1960 \, \text{N} \]
\[ F = 300 \, \malemba{N} + 1960 \, \malemba{N} \]
\[ F = 2260 \, \malemba{N} \]
Kotero, mphamvu yomwe crane imafunika kuti inyamule katundu ndi 2260 N.
Chitsanzo Vuto Lachinayi: Mphamvu mu Dongosolo la Zinthu Ziwiri Zolumikizidwa ndi Chingwe
Funso:
Zinthu ziwiri zolemera makilogalamu 10 ndi makilogalamu 20 motsatana zimalumikizidwa ndi chingwe chopepuka ndipo zimapachikidwa pa pulley. Werengani kuthamanga kwa dongosolo ndi mphamvu ya chingwe pamene dongosololo latulutsidwa kuchokera pamalo opumulira.
Yankho:
Choyamba, tiyeni titchule mphamvu zomwe zimagwira ntchito pa zinthu zonse ziwiri. Tiyeni titchule misa \( m_1 = 10 \, \text{kg} \) ndi misa \( m_2 = 20 \, \text{kg} \). Mphamvu yokoka yomwe imagwira ntchito pa zinthu zonse ziwiri ndi:
\[ F_{g1} = m_1 g = (10 \, \text{kg})(9,8 \, \text{m/s}^2) = 98 \, \text{N} \]
\[ F_{g2} = m_2 g = (20 \, \text{kg})(9,8 \, \text{m/s}^2) = 196 \, \text{N} \]
Popeza dongosololi limatulutsidwa kuchokera ku mpumulo, kufulumira kwa dongosololi kungawerengedwe pogwiritsa ntchito Lamulo Lachiwiri la Newton. Kuthamanga konse (\( a \)) kwa dongosololi ndi:
\[ (m_1 + m_2)a = F_{g2} – F_{g1} \]
\[ (10 \, \text{kg} + 20 \, \text{kg})a = 196 \, \text{N} – 98 \, \text{N} \]
\[ 30 \, \text{kg} \cdot a = 98 \, \text{N} \]
\[ a = \frac{98 \, \text{N}}{30 \, \text{kg}} \]
\[ a = 3,27 \, \text{m/s}^2 \]
Tsopano, tikuwerengera mphamvu mu chingwe (\( T \)). Mphamvu mu chingwe ikhoza kuwerengedwa pogwiritsa ntchito lamulo lachiwiri la Newton pa chimodzi mwa zinthu zazikulu, mwachitsanzo \( m_1 \):
\[ T – m_1 g = m_1 a \]
\[ T – 98 \, \text{N} = (10 \, \text{kg})(3,27 \, \text{m/s}^2) \]
\[ T – 98 \, \malemba{N} = 32,7 \, \malemba{N} \]
\[ T = 32,7 \, \malemba{N} + 98 \, \malemba{N} \]
\[ T = 130,7 \, \malemba{N} \]
Kotero, kuthamanga kwa dongosololi ndi 3,27 m/s² ndipo mphamvu ya chingwe ndi 130,7 N.
Mapeto
Kudzera mu zitsanzo zosiyanasiyana za Lamulo Lachiwiri la Newton, taphunzira momwe mfundoyi imagwiritsidwira ntchito powerengera mphamvu, kuthamanga, ndi kupsinjika m'mikhalidwe yosiyanasiyana. Lamulo Lachiwiri la Newton silofunikira kokha mu sayansi ya chiphunzitso komanso lili ndi ntchito zambiri zothandiza pamoyo watsiku ndi tsiku komanso ukadaulo. Mwa kumvetsetsa ndikuchita Lamulo Lachiwiri la Newton, titha kuthetsa mavuto osiyanasiyana amakina moyenera komanso molondola.
