Knowledge (XXG)

Talk:Circular orbit

Source 📝

189: 74: 53: 179: 158: 22: 84: 700:
Why the gamma factor has been introduced? And how? I mean, as far I know the gamma factor is a construct of and for special relativity. I don't understand why the scalar product of two different velocity vectors in any metric is equal to the gamma factor. In other words, why the orbital velocity has
844:
I don't know what textbook was employed here, but this formula for the orbital speed doesn't make a whole lot of sense to me. When you compute the angular momentum for the circular orbit and minimize this angular momentum, you should get the ISCO radius of 3r_s, no? The formula v=(GM/(r-r_s))^(1/2)
1029: 1162:
Late to the party, but the bold r is the position relative to the center of the massive body as a vector. The regular r is the magnitude of this vector, which is also the distance from the center, or the radius.
827: 1146: 629: 570: 520: 727:
I think you mean v = r d\phi/dt? The problem here is that dt doesn't actually measure time relative to the local observer. It's just an arbitrary coordinate. The actual time difference is
465: 310: 347: 1251: 701:
been defined through the gamma factor and, for example in spherical coordinates, not simply as v(r) = r d\phi/dr? In that case I obtain a different result. What is the difference?
904: 765: 384: 420: 1078: 656:
The equation of motion became redundant, and I really don't see what mentionning the Virial theorem or the delta V brought to the topic. Headbomb 03:33, 17 May 2007 (UTC)
845:
doesn't appear to give the correct ISCO radius when you follow this method. You do get the correct ISCO radius if you use the standard formula v=(GM/r)^(1/2), however.
956: 245: 927: 140: 1231: 130: 685:
I'm aware this is an old question, but it looks bad unanswered. Yes, there are differences and I attempted to describe how to calculate the speed in GR.
1236: 1226: 106: 1246: 235: 675:
Is the orbital velocity of circular orbits in general relativity exactly the same as in the Newtonian case or are there any subtle differences?
188: 1241: 211: 97: 58: 1203: 852: 770: 202: 163: 1087: 33: 716: 270:
I don't know if I'm just retarded and I'm missing something complete obvious, but it seems to me that the speed is given by
953:
This is the first time I'm looking at these equations, can someone clarify what the two different R's are in the equation:
1046: 577: 525: 473: 1153: 574:
And also, if we're talking about circular orbits, might as well give the real orbital energy conservation equation
428: 273: 315: 39: 21: 1207: 856: 1199: 1034: 848: 704: 1168: 1149: 938: 870: 834: 712: 690: 210:
on Knowledge (XXG). If you would like to participate, please visit the project page, where you can join
105:
on Knowledge (XXG). If you would like to participate, please visit the project page, where you can join
1042: 730: 352: 1164: 1080:
in all cases is radius. I do not understand why it is presented as it is, and further, the article
934: 930: 830: 708: 686: 389: 1038: 1024:{\displaystyle \mathbf {a} =-{\frac {v^{2}}{r}}{\frac {\mathbf {r} }{r}}=-\omega ^{2}\mathbf {r} } 634:
It's as if someone went through this and purposely screwed things up. Anyway I cleaned things up.
1061: 89: 1081: 1186: 909: 194: 73: 52: 1220: 676: 661: 642: 1148:, and for the sake of clarity, I am going to replace the former with the later. 178: 157: 102: 184: 79: 1211: 1172: 1157: 1050: 942: 860: 838: 720: 694: 679: 664: 645: 207: 867:
How do you calculate the angular momentum? The conserved quantity is
631:. I have no clue why it was equal to something other than 0 before. 1183:
The definition of the standard gravitational parameter from here:
1194: 929:(because of the issue with time mentioned above in my answer to 822:{\displaystyle {\frac {1}{\sqrt {g_{tt}}}}r{\frac {d\phi }{dt}}} 15: 1179:
standard gravitational parameter does not agree with link.
1141:{\displaystyle a\,={\frac {v^{2}}{r}}\,={\omega ^{2}}{r}} 1187:
http://en.wikipedia.org/Standard_gravitational_parameter
767:
in Schwarzschild metric. If you take this into account,
1090: 1064: 959: 912: 873: 773: 733: 580: 528: 476: 431: 393: 356: 318: 276: 641:
The energy is not zero. The formulas were correct.--
624:{\displaystyle {v^{2} \over {2}}-{\mu \over {r}}=0} 206:, a collaborative effort to improve the coverage of 101:, a collaborative effort to improve the coverage of 565:{\displaystyle T=2\pi {\sqrt {r^{3} \over {\mu }}}} 515:{\displaystyle T=\pi {\sqrt {2r^{3} \over {\mu }}}} 1140: 1072: 1023: 921: 898: 821: 759: 623: 564: 514: 459: 422:. On the orbit, total energy is minimized (E=0). 414: 378: 341: 304: 1195:http://en.wikipedia.org/Circular_orbit#Velocity 1252:Start-Class physics articles of Mid-importance 652:Equation of Motion, delta V and Virial theorem 8: 460:{\displaystyle v={\sqrt {2\mu \over {r}}}} 305:{\displaystyle v={\sqrt {2\mu \over {r}}}} 19: 1197: 846: 702: 342:{\displaystyle v={\sqrt {\mu \over {r}}}} 152: 47: 1133: 1126: 1121: 1105: 1099: 1089: 1065: 1063: 1016: 1010: 990: 988: 977: 971: 960: 958: 911: 885: 884: 878: 872: 799: 784: 774: 772: 740: 734: 732: 608: 603: 593: 587: 581: 579: 554: 548: 541: 527: 504: 497: 486: 475: 449: 438: 430: 407: 391: 371: 364: 354: 331: 325: 317: 294: 283: 275: 1191:does not agree with the text from here: 1116: 1094: 1082:Circular_motion#Uniform_circular_motion 154: 115:Knowledge (XXG):WikiProject Spaceflight 49: 671:Orbital velocity in general relativity 470:This error carries on to the period. 7: 200:This article is within the scope of 95:This article is within the scope of 1232:Low-importance spaceflight articles 899:{\displaystyle r^{2}{\dot {\phi }}} 220:Knowledge (XXG):WikiProject Physics 38:It is of interest to the following 760:{\displaystyle {\sqrt {g_{tt}}}dt} 637:Headbomb 03:22, 17 May 2007 (UTC) 14: 1237:WikiProject Spaceflight articles 1227:Start-Class spaceflight articles 1066: 1017: 991: 961: 379:{\displaystyle mv^{2} \over {2}} 349:. I mean, the kinetic energy is 187: 177: 156: 118:Template:WikiProject Spaceflight 82: 72: 51: 20: 1247:Mid-importance physics articles 240:This article has been rated as 135:This article has been rated as 1051:20:07, 27 September 2012 (UTC) 415:{\displaystyle -GMm \over {r}} 1: 1212:09:05, 19 February 2015 (UTC) 1173:13:54, 13 November 2020 (UTC) 943:12:41, 13 November 2020 (UTC) 861:19:15, 17 December 2019 (UTC) 839:12:41, 13 November 2020 (UTC) 829:is actually the same result. 721:18:54, 16 February 2019 (UTC) 695:23:34, 21 February 2012 (UTC) 680:12:57, 11 November 2007 (UTC) 386:and the potential energy is : 214:and see a list of open tasks. 109:and see a list of open tasks. 1242:Start-Class physics articles 1073:{\displaystyle \mathbf {r} } 906:, which isn't equivalent to 223:Template:WikiProject Physics 1158:19:43, 2 January 2015 (UTC) 1268: 246:project's importance scale 141:project's importance scale 665:12:58, 22 June 2007 (UTC) 646:12:53, 22 June 2007 (UTC) 239: 172: 134: 67: 46: 1084:presents the formula as 98:WikiProject Spaceflight 1142: 1074: 1058:As far as I can tell, 1025: 923: 900: 823: 761: 625: 566: 516: 461: 416: 380: 343: 306: 28:This article is rated 1143: 1075: 1026: 924: 901: 824: 762: 626: 567: 517: 462: 417: 381: 344: 307: 32:on Knowledge (XXG)'s 1088: 1062: 957: 910: 871: 771: 731: 578: 526: 474: 429: 390: 353: 316: 274: 121:spaceflight articles 949:More details please 203:WikiProject Physics 1138: 1117: 1095: 1070: 1021: 922:{\displaystyle rv} 919: 896: 819: 757: 621: 562: 512: 457: 406: 370: 339: 302: 90:Spaceflight portal 34:content assessment 1214: 1202:comment added by 1114: 1054: 1037:comment added by 998: 986: 893: 863: 851:comment added by 817: 794: 793: 749: 723: 707:comment added by 613: 598: 560: 559: 510: 509: 455: 454: 412: 376: 337: 336: 300: 299: 260: 259: 256: 255: 252: 251: 151: 150: 147: 146: 1259: 1150:T.Randall.Scales 1147: 1145: 1144: 1139: 1137: 1132: 1131: 1130: 1115: 1110: 1109: 1100: 1079: 1077: 1076: 1071: 1069: 1053: 1031: 1030: 1028: 1027: 1022: 1020: 1015: 1014: 999: 994: 989: 987: 982: 981: 972: 964: 928: 926: 925: 920: 905: 903: 902: 897: 895: 894: 886: 883: 882: 828: 826: 825: 820: 818: 816: 808: 800: 795: 792: 791: 779: 775: 766: 764: 763: 758: 750: 748: 747: 735: 660:I restored it.-- 630: 628: 627: 622: 614: 612: 604: 599: 597: 592: 591: 582: 571: 569: 568: 563: 561: 558: 553: 552: 543: 542: 521: 519: 518: 513: 511: 508: 503: 502: 501: 488: 487: 466: 464: 463: 458: 456: 453: 448: 440: 439: 421: 419: 418: 413: 411: 392: 385: 383: 382: 377: 375: 369: 368: 355: 348: 346: 345: 340: 338: 335: 327: 326: 311: 309: 308: 303: 301: 298: 293: 285: 284: 228: 227: 226:physics articles 224: 221: 218: 197: 192: 191: 181: 174: 173: 168: 160: 153: 123: 122: 119: 116: 113: 92: 87: 86: 85: 76: 69: 68: 63: 55: 48: 31: 25: 24: 16: 1267: 1266: 1262: 1261: 1260: 1258: 1257: 1256: 1217: 1216: 1215: 1189: 1181: 1122: 1101: 1086: 1085: 1060: 1059: 1032: 1006: 973: 955: 954: 951: 908: 907: 874: 869: 868: 809: 801: 780: 769: 768: 736: 729: 728: 673: 654: 583: 576: 575: 544: 524: 523: 493: 489: 472: 471: 441: 427: 426: 388: 387: 360: 351: 350: 314: 313: 286: 272: 271: 268: 225: 222: 219: 216: 215: 193: 186: 166: 120: 117: 114: 111: 110: 88: 83: 81: 61: 29: 12: 11: 5: 1265: 1263: 1255: 1254: 1249: 1244: 1239: 1234: 1229: 1219: 1218: 1193: 1185: 1180: 1177: 1176: 1175: 1160: 1136: 1129: 1125: 1120: 1113: 1108: 1104: 1098: 1093: 1068: 1019: 1013: 1009: 1005: 1002: 997: 993: 985: 980: 976: 970: 967: 963: 950: 947: 946: 945: 918: 915: 892: 889: 881: 877: 842: 841: 815: 812: 807: 804: 798: 790: 787: 783: 778: 756: 753: 746: 743: 739: 698: 697: 672: 669: 668: 667: 653: 650: 649: 648: 620: 617: 611: 607: 602: 596: 590: 586: 557: 551: 547: 540: 537: 534: 531: 507: 500: 496: 492: 485: 482: 479: 452: 447: 444: 437: 434: 410: 405: 402: 399: 396: 374: 367: 363: 359: 334: 330: 324: 321: 297: 292: 289: 282: 279: 267: 264: 262: 258: 257: 254: 253: 250: 249: 242:Mid-importance 238: 232: 231: 229: 212:the discussion 199: 198: 195:Physics portal 182: 170: 169: 167:Mid‑importance 161: 149: 148: 145: 144: 137:Low-importance 133: 127: 126: 124: 107:the discussion 94: 93: 77: 65: 64: 62:Low‑importance 56: 44: 43: 37: 26: 13: 10: 9: 6: 4: 3: 2: 1264: 1253: 1250: 1248: 1245: 1243: 1240: 1238: 1235: 1233: 1230: 1228: 1225: 1224: 1222: 1213: 1209: 1205: 1204:98.125.78.211 1201: 1196: 1192: 1188: 1184: 1178: 1174: 1170: 1166: 1161: 1159: 1155: 1151: 1134: 1127: 1123: 1118: 1111: 1106: 1102: 1096: 1091: 1083: 1057: 1056: 1055: 1052: 1048: 1044: 1040: 1036: 1011: 1007: 1003: 1000: 995: 983: 978: 974: 968: 965: 948: 944: 940: 936: 932: 916: 913: 890: 887: 879: 875: 866: 865: 864: 862: 858: 854: 853:213.10.18.209 850: 840: 836: 832: 813: 810: 805: 802: 796: 788: 785: 781: 776: 754: 751: 744: 741: 737: 726: 725: 724: 722: 718: 714: 710: 706: 696: 692: 688: 684: 683: 682: 681: 678: 670: 666: 663: 659: 658: 657: 651: 647: 644: 640: 639: 638: 635: 632: 618: 615: 609: 605: 600: 594: 588: 584: 572: 555: 549: 545: 538: 535: 532: 529: 505: 498: 494: 490: 483: 480: 477: 468: 450: 445: 442: 435: 432: 423: 408: 403: 400: 397: 394: 372: 365: 361: 357: 332: 328: 322: 319: 295: 290: 287: 280: 277: 265: 263: 247: 243: 237: 234: 233: 230: 213: 209: 205: 204: 196: 190: 185: 183: 180: 176: 175: 171: 165: 162: 159: 155: 142: 138: 132: 129: 128: 125: 108: 104: 100: 99: 91: 80: 78: 75: 71: 70: 66: 60: 57: 54: 50: 45: 41: 35: 27: 23: 18: 17: 1198:— Preceding 1190: 1182: 1033:— Preceding 952: 847:— Preceding 843: 703:— Preceding 699: 674: 655: 636: 633: 573: 469: 424: 269: 261: 241: 201: 136: 96: 40:WikiProjects 425:Therefore : 112:Spaceflight 103:spaceflight 59:Spaceflight 30:Start-class 1221:Categories 1200:unsigned 1165:Ebvalaim 1047:contribs 1035:unsigned 935:Ebvalaim 931:Dundanox 849:unsigned 831:Ebvalaim 717:contribs 709:Dundanox 705:unsigned 687:Ebvalaim 677:Agge1000 312:and not 1039:Nhilton 662:Patrick 643:Patrick 244:on the 217:Physics 208:Physics 164:Physics 139:on the 36:scale. 1208:talk 1169:talk 1154:talk 1043:talk 939:talk 857:talk 835:talk 713:talk 691:talk 522:not 933:). 266:WTF 236:Mid 131:Low 1223:: 1210:) 1171:) 1156:) 1124:ω 1049:) 1045:• 1008:ω 1004:− 969:− 941:) 891:˙ 888:ϕ 859:) 837:) 806:ϕ 719:) 715:• 693:) 606:μ 601:− 556:μ 539:π 506:μ 484:π 467:. 446:μ 395:− 329:μ 291:μ 1206:( 1167:( 1152:( 1135:r 1128:2 1119:= 1112:r 1107:2 1103:v 1097:= 1092:a 1067:r 1041:( 1018:r 1012:2 1001:= 996:r 992:r 984:r 979:2 975:v 966:= 962:a 937:( 917:v 914:r 880:2 876:r 855:( 833:( 814:t 811:d 803:d 797:r 789:t 786:t 782:g 777:1 755:t 752:d 745:t 742:t 738:g 711:( 689:( 619:0 616:= 610:r 595:2 589:2 585:v 550:3 546:r 536:2 533:= 530:T 499:3 495:r 491:2 481:= 478:T 451:r 443:2 436:= 433:v 409:r 404:m 401:M 398:G 373:2 366:2 362:v 358:m 333:r 323:= 320:v 296:r 288:2 281:= 278:v 248:. 143:. 42::

Index


content assessment
WikiProjects
WikiProject icon
Spaceflight
WikiProject icon
Spaceflight portal
WikiProject Spaceflight
spaceflight
the discussion
Low
project's importance scale
WikiProject icon
Physics
WikiProject icon
icon
Physics portal
WikiProject Physics
Physics
the discussion
Mid
project's importance scale
Patrick
12:53, 22 June 2007 (UTC)
Patrick
12:58, 22 June 2007 (UTC)
Agge1000
12:57, 11 November 2007 (UTC)
Ebvalaim
talk

Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.