1. Lub ntsiab lus ntawm nruab nrab ntawm lub ntiajteb txawj nqus
Ib lub cev khov kho muaj ntau yam khoom me me; yog li ntawd, lub zog gravitational ua rau txhua yam khoom me me no. Hauv lwm lo lus, txhua yam khoom me me muaj nws qhov hnyav. Qhov chaw nruab nrab ntawm lub ntiajteb txawj nqus ntawm ib yam khoom yog ib qho chaw ntawm yam khoom uas qhov hnyav ntawm txhua qhov ntawm yam khoom raug suav hais tias yog qhov chaw nruab nrab ntawm qhov ntawd.
Yog tias ib yam khoom zoo ib yam (qhov ceev ntawm txhua feem ntawm yam khoom zoo ib yam lossis yam khoom muaj cov khoom zoo sib xws) thiab cov duab ntawm yam khoom zoo sib xws (piv txwv li plaub fab, plaub fab plaub fab, lub voj voog)
ces qhov hnyav ntawm yam khoom sib npaug nrog qhov chaw nruab nrab ntawm qhov hnyav ntawm yam khoom, nyob ntawm qhov chaw nruab nrab ntawm yam khoom. Rau cov duab peb ceg, qhov chaw nruab nrab ntawm qhov hnyav nyob ntawm 1/3 h (h = qhov siab ntawm daim duab peb ceg).
2. Kab zauv ntawm qhov chaw ntawm lub ntiajteb txawj nqus
Yog tias cov duab ntawm cov khoom yog symmetrical thiab cov khoom yog homogeneous, ces qhov chaw ntawm lub ntiajteb txawj nqus ntawm cov khoom sib xws nrog qhov chaw ntawm qhov hnyav ntawm cov khoom,
qhov twg qhov chaw ntawm lub ntiajteb txawj nqus thiab qhov chaw ntawm pawg nyob hauv nruab nrab ntawm cov khoom. Ntawm qhov tod tes, yog tias cov khoom yog homogeneous tab sis tsis symmetrical, ces qhov chaw ntawm qhov hnyav ntawm cov khoom tuaj yeem txiav txim siab siv cov qauv hauv qab no.
Cov kev sib koom ua ke ntawm qhov hnyav ntawm cov khoom ntawm x-axis:
Cov kev sib koom ua ke ntawm qhov hnyav ntawm cov khoom ntawm y-axis:
x = qhov nruab nrab ntawm cov khoom ntawm x-axis, y = qhov nruab nrab ntawm cov khoom ntawm y-axis, A = thaj chaw. Yog tias cov khoom muaj peb qhov ntev, ntxiv rau kev txiav txim siab qhov sib piv ntawm qhov hnyav ntawm cov khoom ntawm x thiab y axes, nws kuj txiav txim siab qhov sib piv ntawm qhov hnyav ntawm cov khoom ntawm z-axis. Thaj chaw (A) raug hloov los ntawm ntim (V).
Piv txwv teeb meem 1.
Txheeb xyuas qhov sib koom ua ke ntawm qhov chaw ntawm lub ntiajteb txawj nqus ntawm cov khoom sib xws hauv daim duab ntawm sab!
tshuaj:
Faib yam khoom ua peb ntu.
A 1 = (10-0)(10-0) = (10)(10) = 100
A2 = (20-10)(30-0) = (10)(30) = 300
A 3 = (30-20)(10-0) = (10)(10) = 100
x 1 = 1/2 (10-0) = 1/2 (10) = 5
x 2 = 1/2 (20-10) + 10 = 1/2 (10) + 10 = 5 + 10 = 15
x 3 = 1/2 (30-20) + 20 = 1/2 (10) + 20 = 5 + 20 = 25
y 1 = 1⁄2 (10–0) = 1⁄2 (10) = 5
y 2 = 1⁄2 (30–0) = 1⁄2 (30) = 15
y 3 = 1⁄2 (10-0) = 1⁄2 (10) = 5
Cov kev sib koom ua ke ntawm qhov hnyav ntawm cov khoom ntawm x-axis:
Cov kev sib koom ua ke ntawm qhov hnyav ntawm cov khoom ntawm y-axis:
Cov kev sib koom ua ke ntawm qhov hnyav ntawm yam khoom yog (15; 11)
Piv txwv teeb meem 2.
Txheeb xyuas cov coordinates ntawm qhov hnyav ntawm yam khoom hauv daim duab!
tshuaj:
Faib cov khoom ua ob ntu, thaj tsam 1 = plaub fab, thaj tsam 2 = peb ceg.
A 1 = (5-1)(3-0) = (4)(3) = 12
A 2 = 1/2 (6-0)(9-3) = 1/2 (6)(6) = (3)(6) = 18
x 1 = 1/2 (5-1) + 1 = 1/2 (4) + 1 = 2 + 1 = 3
x 2 = 1/2 (6-0) = 1/2 (6) = 3
y 1 = 1⁄2 (3-0) = 1⁄2 (3) = 1.5
y 2 = 1/3(9-3) + 3 = 1/3(6) + 3 = 2 + 3 = 5
Cov kev sib koom ua ke ntawm qhov hnyav ntawm cov khoom ntawm x-axis:
Cov kev sib koom ua ke ntawm qhov hnyav ntawm cov khoom ntawm y-axis:
Qhov sib koom ua ke ntawm qhov hnyav ntawm yam khoom yog (3; 3.6)
