1. Aia kekahi kanaka i loko o kahi eleweka e neʻe ana i luna ma ka wikiwiki mau . ʻO ke kaumaha o ke kanaka he 800 N. Ua haki koke ke kaula eleweka, no laila ua hāʻule ka eleweka. E hoʻoholo i ka ikaika maʻamau i hana ʻia e ka papahele o ka eleweka i ke kanaka ma mua pono a ma hope o ka haki ʻana o ke kaula o ka eleweka.
A. 800 N a me 0
B. 800 N a me 800 N
C. 1600 N a me 0
D. 1600 ʻĀkau a me 800 ʻĀkau
ʻIke ʻia:
Kaumaha (w) = 800 Newton
Makemake ʻia: ʻO ka ikaika maʻamau (N)
Lōlā:
Ma mua o ka haki ʻana o ke kaula o ka elevator
Ke kū ke kanaka ma ka papahele o ka eleweka, hana ke kaumaha ma luna o ke kanaka ma kahi e iho ai ke kuhikuhi o ke kanaka. Ua hoʻomaha kēlā kanaka no laila pono e hana ka ikaika maʻamau ma luna o ke kanaka, kahi e piʻi ai ke kuhikuhi o ka ikaika maʻamau a ua like ka nui o ka ikaika maʻamau me ka nui o ke kaumaha.
No ka mea, ua hoʻomaha ke kanaka i loko o ka elevator a neʻe ka elevator i ka wikiwiki mau (ʻaʻohe ka piʻi), no laila ʻaʻohe mana e hana ma luna o ke kanaka.
∑F = 0
N – w = 0
N = w
N = 800 Newton
Ma hope o ka haki ʻana o ke kaula o ka elevator
Ma hope o ka haki ʻana o ke kaula o ka eleweka, hāʻule pū ka eleweka a me ke kanaka manuahi , kahi i like ai ka nui a me ke kuhikuhi o ko lākou wikiwiki me ka wikiwiki ma muli o ke koʻikoʻi. ʻAʻohe ikaika maʻamau ma luna o ke kanaka.
ʻO ka pane pololei ʻo A.
2. Neʻe kahi poloka me ke kaumaha o 20 grams ma ka wikiwiki mau ma luna o kahi papahele ʻāwiliwili ma ka wikiwiki mau inā he ikaika kūwaho o 2 N e hana ana ma ka poloka. E hoʻoholo i ka nui o ka ikaika friction i ʻike ʻia e ka poloka.
A. 0.3 N
B. 1.4 N
C. 2.0 N
D. 3.6 N
ʻIke ʻia:
Nuipaʻa (m) = 20 grams
Ikaika (F) = 2 Newton
Makemake ʻia: Ka nui o ka ikaika friction i ʻike ʻia e ka poloka.
Lōlā:
Ma muli o ke kānāwai mua o ka neʻe ʻana o Newton, inā neʻe kahi poloka ma ka wikiwiki mau, a laila ʻaʻohe wikiwiki o ka poloka. Neʻe ka poloka ma ka wikiwiki mau, a ʻaʻohe wikiwiki inā:
– Ua like ka nui o ka ikaika kuʻi (F fric ) me ka nui o ka ikaika waho (F)
– ʻO ke kuhikuhi o ka ikaika friction (F fric ) he ʻaoʻao ʻē aʻe ia i ka ikaika waho (F)
E hoʻopili i ke kānāwai mua o ka neʻe ʻana o Newton:
∑ F = 0
F – F fric = 0
F = F fric
F fric = 2 Newton
ʻO ka pane pololei ʻo C.
3. He ʻāpana pālahalaha laumania me ka lōʻihi o 0.6 m a me ke kiʻekiʻe o 0.4 m. E neʻe i luna kahi poloka me ke kaumaha o, 1350 N me ka hoʻohana ʻana i ka ʻāpana pālahalaha. E hoʻoholo i ka nui o ka ikaika e pono ai e hoʻoneʻe i ka poloka.
A. 100 N
B. 300 N
C. 600 N
D. 900 N
ʻIke ʻia:
Kaumaha o ka poloka (w) = 1350 Newtons
hyp = 0.6 m
kū'ē = 0.4 m
Makemake ʻia: ʻO ka ikaika liʻiliʻi loa
Lōlā:
hyp = ac = 0.6 m
kū'ē = bc = 0.4 m
Ka hewa θ = bc / ac = 0.4 / 0.6 = 4/6 = 2/3
Ma muli o ke kānāwai mua o ka neʻe ʻana o Newton, hoʻomaka ka poloka e neʻe i luna a laila ʻo ka ikaika waho (F) ma ka liʻiliʻi like me ka ʻāpana pae o ke kaumaha (wx ).
∑ F = 0
F – w x = 0
F = wx
Inā ʻo F = w x , a laila hoʻomaka ka mea e neʻe i luna ma ka wikiwiki mau.
w x = w hewa θ = (1350)(2/3) = (2)(450) = 900 Newtons
ʻO D ka pane pololei.
4. ʻEkolu mau mana, ʻo F 1 = 22 N, F 2 = 18 N a me F 3 = 40 N e hana ana ma kahi poloka. ʻO wai ke kiʻi e wehewehe ana i ke kānāwai mua o Newton.
Lōlā:
Ke kānāwai mua o Newton: Ka ikaika ʻupena (ΣF) = 0.
A. F 1 + F 2 – F 3 = 22 N + 18 N – 40 N = 40 N – 40 N = 0
B. F 2 + F 3 – F 1 = 18 N + 40 N – 22 N = 58 N – 22 N = 36 N (ʻākau)
C. F 2 + F 3 – F 1 = 18 N + 40 N – 22 N = 58 N – 22 N = 36 N (ʻākau)
D. F 1 + F 3 – F 2 = 22 N + 40 N – 18 N = 62 N – 18 N = 44 N (hema)
