Ka mālama ʻana i ka ikehu mechanical ma nā ʻili piʻo - nā pilikia a me nā hoʻonā
1. Inā he 6 m/s ka wikiwiki o ka pōpō ma ke kiko A, ʻo ka wikiwiki o ka pōpō ma ke kiko B he √92 m/s, a ʻo ka wikiwiki ma muli o ke koʻikoʻi he g = 10 m/s 2. He aha ke kiʻekiʻe o ke kiko B (h)?
ʻIke ʻia:
Ka wikiwiki o ka pōpō ma ke kiko A (v)A) = 6 m/s
Ka wikiwiki o ka pōpō ma ke kiko B (v B ) = √92 m/s
Ka wikiwiki ma muli o ke koʻikoʻi (g) = 10 m/s 2
ʻO ke kiʻekiʻe o A (h A ) = 5.6 mika
ʻO ke kiʻekiʻe o B (h B ) = h
Makemake ʻia: Ke kiʻekiʻe o ke kiko B (h)
Lōlā:
ʻO ka ikehu mechanical mua = ka ikehu hiki ke hoʻopaʻa ʻia
Ma ke kiko A, ʻo ka wikiwiki o ka pōpō = 0, no laila ʻo ka ikehu kinetic o ka pōpō = 0. KE = 1/2 mv 2 = 1/2 m (0) = 0.
Pōpō ma ke kiʻekiʻe o 5.6 mika no laila loaʻa i ka pōpō ka ikehu hiki ke hoʻopaʻa ʻia. ʻO ka ikehu hiki ke hoʻopaʻa ʻia : PE = mgh = m (10)(5.6) = 56 m
ʻO ka ikehu mechanical mua = ka ikehu hiki ke hoʻopaʻa ʻia ke kaumaha + ikehu kinetic = 56 m + 0 = 56 m
ʻO ka ikehu mechanical hope loa = ka ikehu hiki ke hoʻopaʻa ʻia ka umekaumaha + ikehu kinetic
Ma ke kiko B, ʻo ke kiʻekiʻe o ka pōpō ʻo h. ʻO ka ikehu hiki ke hoʻopaʻa ʻia e ka umekaumaha: PE = mgh = m (10) h = 10 mh
ʻO ka ikehu kinetic o ka pōpō: KE = 1/2 mv 2 = 1/2 m (√92) 2 = 1/2 m (92) = 46 m
ʻO ka ikehu mechanical hope loa = ka ikehu hiki ke hoʻoulu ʻia e ka umekaumaha + ka ikehu kinetic = 10 mh + 46 m = m (10 h + 46)
ʻO ke kumumanaʻo o ka mālama ʻana i ka ikehu mechanical:
ʻO ka ikehu mechanical mua = ka ikehu mechanical hope loa
56 m = m (10 h + 46)
56 = 10 hola + 46
56 – 46 = 10 hola
10 = 10 hola
h = 10/10
h = 1 mika
2.
Inā ʻo ka wikiwiki mua = 0, ʻo ka wikiwiki ma muli o ke koʻikoʻi = 10 m/s² , a laila he aha ka wikiwiki ma ke kiʻekiʻe o B.
ʻIke ʻia:
ʻO ka wikiwiki mua (v o ) = 0
ʻO ke kiʻekiʻe mua (h o ) = 50 m – 10 m = 40 m
ʻO ke kiʻekiʻe hope loa (h t ) = 0
Ka wikiwiki ma muli o ke koʻikoʻi (g) = 10 ms -2
Makemake ʻia: ʻO ka wikiwiki hope loa ( vt )
Lōlā:
Ka loli o ka ikehu kinetic:
ΔKE = 1/2 m (v t 2 – v o 2 ) = 1/2 m (v t 2 – 0) = 1/2 mv t 2
Ka loli o ka ikehu hiki:
ΔPE = mg (ht – h o ) = m (10)(0-40) = m (10)(-40) = – 400 m
E helu i ka wikiwiki hope loa (vt ) me ka hoʻohana ʻana i ka hoohalike o ke kumumanaʻo o ka mālama ʻana i ka ikehu mechanical :
0 = ΔKE + ΔPE
0 = 1/2 mv t 2 – 400 m
1/2 mv t 2 = 400 m
1/2 v t 2 = 400
v t 2 = 2(400)
vt = √(400)(2)
vt = 20√2 m/ s
- He aha ke ʻano o ka "mālama ʻana i ka ikehu mechanical"?
- pane mai: ʻO ka mālama ʻana i ka ikehu mechanical ʻo ia hoʻi ka ikehu mechanical holoʻokoʻa (ka huina o ka ikehu kinetic a me ka ikehu hiki) o kahi ʻōnaehana kaʻawale e mau ana inā he mau mana conservative wale nō, e like me ke umekaumaha, e hana ma luna.
- Pehea e mālama ai kahi mea e neʻe ana ma luna o kahi ʻili piʻo (e like me ka pōpō e ʻōwili ana i lalo o kahi alapiʻi piʻo) i kona ikehu mechanical?
- pane mai: I ka neʻe ʻana o ka mea i lalo o ka ʻili piʻo, hoʻololi ʻia ka ikehu hiki ke hana i ikehu kinetic, akā e mau ana ka ikehu mechanical holoʻokoʻa, me ka manaʻo ʻaʻohe mana non-conservative (e like me ka friction) e hana ana i ka hana.
- Inā hoʻokuʻu ʻia kahi pōpō mai ka hoʻomaha ma ka piko o kahi alapiʻi piʻo, pehea e loli ai kona ikehu kinetic i kona neʻe ʻana i lalo o ke alapiʻi?
- pane mai: Hoʻonui ʻia ka ikehu kinetic o ka pōpō i kona neʻe ʻana i lalo o ke alapiʻi no ka mea ua emi iho kona ikehu hiki ke hoʻololi ʻia i ikehu kinetic.
- I ka loaʻa ʻole o ka friction, pehea e hoʻohālikelike ʻia ai ka wikiwiki o ka pōpō ma lalo o kahi paheʻe piʻo me kahi paheʻe pololei o ke kiʻekiʻe like?
- pane mai: E like ka wikiwiki o ka pōpō ma lalo no nā paheʻe piʻo a me nā paheʻe pololei no ka mea, ʻo ka hoʻololi ʻana o ka ikehu hiki ke hana i ka ikehu kinetic e hilinaʻi wale ʻia ma ke kiʻekiʻe kū pololei, ʻaʻole ke ala i lawe ʻia.
- No ke aha e hiki ʻole ai i ka pōpō ke hiki i kona kiʻekiʻe mua ke ʻōwili ʻia i luna o kahi alapiʻi piʻo ma hope o ka iho ʻana mai kahi kiʻekiʻe?
- pane mai: Inā he mau mana kūpaʻa ʻole e like me ka friction e hana ana ma ka pōpō, e hana lākou i ka hana kūʻē i ka neʻe ʻana, e hoʻololi ana i kekahi o ka ikehu mechanical o ka pōpō i nā ʻano ʻē aʻe, e like me ka wela. ʻO ka hopena, ʻaʻole lawa ka ikehu o ka pōpō e hiki ai i kona kiʻekiʻe mua.
- Inā heʻe nā mea ʻelua ʻano like ʻole (e like me ka poepoe a me ka cube) i lalo i kahi alapiʻi piʻo mai ke kiʻekiʻe like me ka ʻole o ka ʻōwili ʻana, e like anei ko lākou wikiwiki ma ka lalo? No ke aha mai?
- pane mai: ʻAe, e like ko lākou wikiwiki ma lalo. Ke manaʻo nei ʻaʻohe ʻōwili a ʻaʻohe friction, ʻo ke kumu wale nō e hoʻoholo ai i ko lākou wikiwiki ʻo ia ka mālama ʻana i ka ikehu ma muli o ke kiʻekiʻe mua, ʻaʻole ko lākou ʻano.
- Pehea ka hopena o ke kūlou ʻana o kahi ʻili i ka ikaika maʻamau ma luna o kahi mea e neʻe ana ma ia mea?
- pane mai: ʻO ke kūlou ke kumu o ka loli ʻana o ke kuhikuhi o ka ikaika maʻamau i ka neʻe ʻana o ka mea. Ma kahi ʻili concave i luna (e like me loko o ke pola), ʻoi aku ka nui o ka ikaika maʻamau ma lalo ma muli o ka ikaika centripetal e pono ai no ka neʻe kūlou. I ka ʻaoʻao ʻē aʻe, ma kahi ʻili convex, hiki i ka ikaika maʻamau ke emi a lilo paha i ʻole (haʻalele ka mea i ka ʻili) ma kahi kiʻekiʻe loa.
- He aha ke kuleana o ka radius o ke curvature i ka mālama ʻana i ka ikehu mechanical ma kahi ʻili piʻo?
- pane mai: ʻAʻole pili pololei ka radius o ke kūlou ʻana i ka mālama ʻana i ka ikehu mechanical. Eia nō naʻe, hiki iā ia ke hoʻololi i ka ikaika maʻamau a, inā he friction, ka nui o ka ikehu i nalowale i nā ikaika non-conservative.
- Inā he ʻūlū ko ke ala i waenakonu (e like me ke kūlou ʻano U), pehea lā e ʻokoʻa ai ka ikehu mechanical o kahi mea i kona neʻe ʻana ma waena o ke ʻūlū a piʻi i luna i kēlā ʻaoʻao?
- pane mai: E emi ana ka ikehu hiki o ka mea i kona neʻe ʻana i loko o ka lua hohonu a hoʻonui i kona ikehu kinetic. I kona neʻe ʻana i luna i kēlā ʻaoʻao, e emi ana kona ikehu kinetic, a e piʻi aʻe kona ikehu hiki. Inā hana wale nā ikaika conservative, e mau ana ka ikehu mechanical holoʻokoʻa i ka neʻe ʻana.
- Hiki i kahi mea ke loaʻa ka ikehu kinetic translational a me ka ikehu kinetic rotational i ka wā e neʻe ai ma luna o kahi ʻili piʻo?
- pane mai: ʻAe, inā ʻōwili kahi mea e like me ka pōpō (me ka paheʻe ʻole) ma luna o kahi ʻili piʻo, e loaʻa iā ia ka ikehu kinetic translational ma muli o kona kikowaena o ka nuipa e neʻe ana a me ka ikehu kinetic rotational ma muli o kona wili ʻana a puni kona axis.
