Tetapan gravitasi

Tetapan gravitasi disimbolkan dengan huruf G, merupakan sebuah tetapan empiris yang digunakan dalam perhitungan gaya gravitasi yang terjadi antara dua benda. Tetapan ini umumnya muncul dalam hukum gravitasi universal Newton dan teori relativitas Einstein.

Tetapan ini sering juga disebut tetapan gravitasi umum atau tetapan Newton dan disimbolkan dengan G besar.^[1] G Besar tidak sama dengan g kecil yang merupakan medan gravitasi lokal,^[2] khususnya di permukaan bumi.

Hukum dan tetapan

Menurut hukum gravitasi universal, gaya tarik (F) antara dua benda proporsional terhadap massa benda (m₁ dan m₂), dan berbanding terbalik proporsional terhadap kuadrat jarak r, (hukum kuadrat terbalik) di antara keduanya:

F=G{\frac {m_{1}m_{2}}{r^{2}}}\

G, adalah tetapan gravitasi.

Tetapan gravitasi sulit diukur secara akurat.^[3] Dalam SSI tahun 2010 direkomendasikan:^[4]

G=6.67384(80)\times 10^{-11}\ {\mbox{m}}^{3}\ {\mbox{kg}}^{-1}\ {\mbox{s}}^{-2}=6.67384(80)\times 10^{-11}\ {\rm {N}}\,{\rm {(m/kg)^{2}}}

dengan standar ketidakpastian relatif 1,2×10⁻⁴.^[4]

Catatan kaki

^ "University of Washington Big G Measurement". Astrophysics Science Division. Goddard Space Flight Center. 2002-12-23. Since Cavendish first measured Newton's Gravitational constant 200 years ago, "Big G" remains one of the most elusive constants in physics.
^ Fundamentals of Physics 8ed,Halliday/Resnick/Walker, ISBN 978-0-470-04618-0 p 336
^ George T. Gillies (1997), "The Newtonian gravitational constant: recent measurements and related studies", Reports on Progress in Physics, 60 (2): 151–225, Bibcode:1997RPPh...60..151G, doi:10.1088/0034-4885/60/2/001, diarsipkan dari versi asli tanggal 2019-12-13, diakses tanggal 2012-09-05 . A lengthy, detailed review. See Figure 1 and Table 2 in particular.
^ ^a ^b P.J. Mohr, B.N. Taylor, and D.B. Newell (2011), "The 2010 CODATA Recommended Values of the Fundamental Physical Constants" (Web Version 6.0). This database was developed by J. Baker, M. Douma, and S. Kotochigova. Available: http://physics.nist.gov/constants [Thursday, 02-Jun-2011 21:00:12 EDT]. National Institute of Standards and Technology, Gaithersburg, MD 20899.

Pranala luar

Newtonian constant of gravitation G at the National Institute of Standards and Technology References on Constants, Units, and Uncertainty
The Controversy over Newton's Gravitational Constant Diarsipkan 2010-01-10 di Wayback Machine. — additional commentary on measurement problems
The Gravitational Constant Diarsipkan 2008-12-17 di Wayback Machine.

[1] "University of Washington Big G Measurement". Astrophysics Science Division. Goddard Space Flight Center. 2002-12-23. Since Cavendish first measured Newton's Gravitational constant 200 years ago, "Big G" remains one of the most elusive constants in physics.

[2] Fundamentals of Physics 8ed,Halliday/Resnick/Walker, ISBN 978-0-470-04618-0 p 336

[gillies-3] George T. Gillies (1997), "The Newtonian gravitational constant: recent measurements and related studies", Reports on Progress in Physics, 60 (2): 151–225, Bibcode:1997RPPh...60..151G, doi:10.1088/0034-4885/60/2/001, diarsipkan dari versi asli tanggal 2019-12-13, diakses tanggal 2012-09-05 . A lengthy, detailed review. See Figure 1 and Table 2 in particular.

[2010_CODATA-4] P.J. Mohr, B.N. Taylor, and D.B. Newell (2011), "The 2010 CODATA Recommended Values of the Fundamental Physical Constants" (Web Version 6.0). This database was developed by J. Baker, M. Douma, and S. Kotochigova. Available: http://physics.nist.gov/constants [Thursday, 02-Jun-2011 21:00:12 EDT]. National Institute of Standards and Technology, Gaithersburg, MD 20899.

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