1. Wehewehena o ka ikaika friction
ʻO ka friction kahi huki e hana ana ma waena o nā ʻili o nā mea e pā ana kekahi i kekahi. Ma kēia kumuhana, pili ka ikaika friction i aʻo ʻia i ka ikaika friction e hana ana ma waena o ʻelua mau ʻili kino paʻa e pā ana. E like me ka friction ma waena o ke kumu o ke kaola a me ka ʻili papahele, ka friction ma waena o ke kumu kāmaʻa a me ka ʻili papahele, ka friction ma waena o nā huila o ke kaʻa a me ka ʻili alanui.
Hana mau ka ikaika friction ma luna o ka ʻili o nā mea paʻa e pā ana kekahi i kekahi, ʻoiai he laumania loa nā mea. ʻOiai nā ʻili laumania he ʻoʻoleʻa loa ia ma kahi pae microscopic. Ke neʻe kahi mea, hoʻopilikia kēia mau kualono microscopic i ka neʻe ʻana. Ma ka pae atomika, ʻo kahi puka ma luna o ka ʻili e hoʻokokoke loa i nā ʻātoma i nā ʻili ʻē aʻe, i hiki ai i nā mana uila ma waena o nā ʻātoma ke hana i nā pilina kemika, ma ke ʻano he hui ma waena o ʻelua ʻili o kahi mea e neʻe ana. Ke neʻe kahi mea, no ka laʻana ke paʻi ʻoe i kahi puke ma luna o ka ʻili o ka papaʻaina, ʻike ka neʻe ʻana o ka puke i nā mea pale a pau. ʻO kēia ma muli o ka hoʻokumu ʻia ʻana a me ka hoʻokuʻu ʻia ʻana o ka pilina.
Inā hamo ka ʻili o kahi mea i ka ʻili o kekahi mea ʻē aʻe, hana kēlā me kēia o kēia mau mea ma ka friction ma waena o kekahi. ʻO ka ikaika friction ma luna o ka mea e neʻe ana aia mau ma ke kuhikuhi ʻē aʻe i ke kuhikuhi o ka neʻe ʻana o ka mea. Ma waho aʻe o ke kāohi ʻana i ka neʻe ʻana o nā mea, hiki i ka friction ke hana i ka ʻaʻahu a me ka hōʻino. Hiki iā mākou ke nānā i kēia ma ka ʻenekini kaʻa. No ka laʻana, ke hāʻawi mākou i ka ʻaila lubricating i ka ʻenekini mokokaikala, makemake mākou e hōʻemi i ka ikaika friction e hana ʻia ana i loko o ka ʻenekini. Inā ʻaʻole i hāʻawi ʻia ka ʻaila lubricating, e hōʻino koke ʻia kā mākou ʻenekini kaʻa. ʻO kēia laʻana kekahi o nā pohō i hana ʻia e ka friction.
2. Nā ʻano o nā ikaika kuʻi
ʻElua ʻano o nā ikaika frictional, ʻo ia hoʻi ka ikaika o ka friction static (fs ) a me ka ikaika o ka friction kinetic (fk ) . Hana ka ikaika friction static i ka wā ʻaʻole i neʻe ka mea, ʻoiai hana ka ikaika friction kinetic i ka wā e neʻe ana ka mea. Inā ʻoe e paʻi i kahi papaʻaina, akā ʻaʻole i neʻe ka papaʻaina, a laila ʻo ka ikaika friction e hana ana ma ka papaʻaina e hoʻomaha ana he ikaika friction static. I ka ʻaoʻao ʻē aʻe, i ka wā e neʻe ana ka papaʻaina, ʻo ka ikaika friction e hana ana ma ka papaʻaina he friction kinetic. Inā ʻaʻole i paʻi mau ʻia ka papaʻaina e neʻe ana, e kū ka papaʻaina ma hope o ka neʻe ʻana no kekahi manawa. Kū ka papaʻaina ma muli o ka ikaika friction kinetic e ālai ana i ka neʻe ʻana o ka papaʻaina.
Ua paheʻe paha ʻoe i ka wā e hehi ana ma luna o kahi mea laumania? Ke paheʻe ʻoe, ʻo ka ikaika friction e hana ana ma waena o ke kumu o ke kāmaʻa a i ʻole ka lalo o kahi kāmaʻa me kahi ʻili laumania he friction kinetic. Ua like kēia pilikia me ka wā e neʻe ai kahi mokokaikala a kaʻa paha ma luna o kahi ʻili alanui pulu a laumania, e hoʻōki ana a hiki i ka paheʻe ʻana o ka huila. Ke paheʻe nā huila, ʻo ka ikaika friction e hana ana ma ka ʻili o ka huila a me ka ʻili alanui he ikaika friction kinetic. I ka ʻaoʻao ʻē aʻe, ke hele ʻoe, ʻo ka ikaika friction e hana ana ma waena o ke kumu kāmaʻa a i ʻole ka lalo o nā kāmaʻa me ka ʻili papahele he ikaika friction static. Pēlā nō, ke paheʻe ʻole nā huila, ʻo ka ikaika friction e hana ana ma ka ʻili o ka huila a me ke alanui he friction static.
2.1 Ka ikaika kuʻi paʻa
ʻO ka ikaika friction static ka ikaika frictional e hana ana ma ka ʻili o nā mea e pā ana kekahi i kekahi ke neʻe ʻole nā mea.
Hōʻike ka Kiʻi 1 i kahi mea e kau mau ana ma luna o ka ʻili o kahi mokulele pālahalaha. Inā ʻaʻole i neʻe ka mea, a laila ʻoi aku ka liʻiliʻi o ka ikaika friction static (fs) ma mua o ka ikaika huki (F). Inā hoʻomau ʻia ka huki ʻia ʻana, a laila e neʻe ka mea. Ke neʻe ka mea ʻākau, ʻo ka nui o ka ikaika friction static (fs) ua like ia me ka nui o ka ikaika huki (F).
ʻŌlelo ke Kānāwai Mua o Newton e hoʻomaha nā mea inā he ʻole ka ikaika holoʻokoʻa (ka ikaika hopena).
ΣF y = 0 (Hoʻomaha ka mea a ʻaʻole neʻe i ke kuhikuhi kū pololei)
N – w = 0
N = w (1.2)
E hoʻololi iā N ma ka hoohalike 1.1 me N ma ka hoohalike 1.2
fs = μsw
fs = μs mg (1.3)
fs = ka haʻalulu paʻa (N), μs = ke koina o ka haʻalulu paʻa, N = ka ikaika maʻamau (N), w = ke koʻikoʻi (N), m = ka nuipaʻa (kg), g = ka wikiwiki o ke koʻikoʻi (m/s 2 )
Inā makemake ʻoe e hoʻoholo i ke koina o ka friction static, a laila e hoʻohana i ka hoohalike 1.1 b
Σf x = 0 (Hoʻomaha ka mea a ʻaʻole neʻe i ke kuhikuhi pae)
F – fs = 0
F = fs ( 1.4)
Ke hoʻomaka ka mea e neʻe, ua like ka ikaika friction static kiʻekiʻe loa me ka nui o ka ikaika paʻi a huki paha.
2.2 Ka ikaika kuʻi kinetic
ʻO ka ikaika friction kinetic ka ikaika frictional e hana ana ma ka ʻili o nā mea e pā ana kekahi i kekahi ke neʻe kahi mea.
Inā makemake ʻoe e hoʻoholo i ke koina o ka friction kinetic (μ k ), e hoʻohana i ka hoohalike 1.5 b
Hōʻike ke Kiʻi 2 i kahi mea e huki mau ʻia ana i neʻe ai ka mea i ka wikiwiki mau. Ke neʻe nei i ka wikiwiki mau, ua like ka nui o ka ikaika friction kinetic (fk) me ka nui o ka ikaika huki (F).
ʻŌlelo ke Kānāwai Mua o Newton e neʻe ana kahi mea i ka wikiwiki mau inā ʻaʻohe ka ikaika holoʻokoʻa (ka ikaika hopena).
ΣF x = 0 (neʻe nā mea i ka wikiwiki mau ma ke kuhikuhi pae)
F – f k = 0
F = fk ( 1.6)
Laʻana pilikia 1:
Huki kekahi haumāna i kahi kaola me ke kaumaha o 1 kg e kau ana ma luna o ka papaʻaina me ka hoʻohana ʻana i ka dynamometer (kahi mea ana i ka ikaika). Ke neʻe ka kaola, hōʻike ka dynamometer i ka helu 2 N. Inā ʻo ka wikiwiki o ke koʻikoʻi = 10 m/s 2 , e hoʻoholo (a) ka nui o ka ikaika friction static (b) ke coefficient o ka friction static
pāʻoihana:
ʻIke ʻia : m = 1 kg, F = 2 N, g = 10 m/s 2 , w = mg = 10 N
(a) fs
Ke neʻe ka kukuna, ʻo ka nui o ka ikaika friction static = ka nui o ka ikaika huki (e hoʻohālikelike i ka hoʻohālikelike 1.4). No laila, f s = F = 2 N.
(b) μs
fs = μsw
2 N = (μs ) (10 N)
μ s = 2 N / 10 N = 0.2
Laʻana pilikia 2:
Ua huki mau ʻia kahi kaola me ke kaumaha o 1 kg ma luna o ka ʻili o ka papaʻaina i mea e neʻe ai ke kaola i ka wikiwiki mau. Ke neʻe ke kaola i ka wikiwiki mau, hōʻike ka dynamometer i ka helu 1 N. Inā ʻo ka wikiwiki o ke koʻikoʻi = 10 m/s 2 , e hoʻoholo (a) ka nui o ka ikaika friction kinetic (b) ke koina o ka friction kinetic
pāʻoihana:
ʻIke ʻia: m = 1 kg, g = 10 m/s 2 , F = 1 N, w = mg = 10 N
(a) f k
Ke neʻe mau ka kukuna a neʻe paha i ka wikiwiki mau, ʻo ka nui o ka ikaika friction kinetic = ka nui o ka ikaika huki (e hoʻohālikelike i ka hoʻohālikelike 1.6).
No laila f k = F = 1 N
(b) μk
f k = μ k w
1 N = (μ k )(10 N)
μ k = 1 N / 10 N = 0.1
