A353407 Decimal expansion of the gravitational force between two unit-edge-length unit-mass cubes whose centers are a unit distance apart, so they are in contact along one face, in units where the gravitational constant is G = 1.

9, 2, 5, 9, 8, 1, 2, 6, 0, 5, 5, 7, 2, 9, 1, 4, 2, 8, 0, 9, 3, 4, 3, 6, 6, 8, 7, 0, 3, 8, 3, 3, 1, 5, 5, 9, 9, 0, 6, 4, 2, 5, 4, 1, 4, 2, 8, 2, 7, 7, 7, 8, 6, 5, 5, 9, 8, 7, 3, 4, 3, 4, 5, 4, 0, 9, 5, 9, 8, 4, 2, 2, 4, 9, 8, 6, 3, 2, 8, 6, 2, 2, 1, 4, 8, 5, 4, 1, 6, 8, 0, 8, 2, 6, 5, 1, 3, 3, 4, 0, 8, 5, 4, 0, 1

Offset

0,1

Comments

The absolute value of the total gravitational attraction force between two identical homogeneous cubes, each with mass M and edge length s, whose centers are at distance s is c*G*M^2/s^2, where G is the gravitational constant (A070058) and c is this constant.

The calculation of the closed-form formula for this constant was done by Prof. Bengt Fornberg of the University of Colorado (Trefethen, 2011).

Links

Table of n, a(n) for n=0..104.

Folkmar Bornemann, The Challenge of Sixfold Integrals: The Closed-Form Evaluation of Newton Potentials between Two Cubes, arXiv:2204.02793 [math.CA], 2022.

Jeff Sanny and David M. Smith, How Spherical Is a Cube (Gravitationally)?, The Physics Teacher, Vol. 53 (2015), pp. 111-113; alternative link.

Lloyd N. Trefethen, Ten digit problems, in: D. Schleicher and M. Lackmann (eds.), An Invitation to Mathematics, Springer, Berlin, Heidelberg, 2011, pp. 119-136; alternative link.

Lloyd N. Trefethen, Two Cubes, LMS Newsletter, Issue 491 (November 2020), p. 17.

Michael Trott, Calculating the energy between two cubes, News, Views and Insights from Wolfram, Wolfram Blog, October 23, 2012.

Formula

Equals (26*Pi/3 - 14 + 2*sqrt(2) - 4*sqrt(3) + 10*sqrt(5) - 2*sqrt(6) + 26*log(2) - 2*log(5) + 10*log(sqrt(2) + 1) + 20*log(sqrt(3) + 1) - 35*log(sqrt(5) + 1) + 6*log(sqrt(6) + 1) - 2*log(sqrt(6) + 4) - 22*arctan(2*sqrt(6)))/3.

Example

0.92598126055729142809343668703833155990642541428277...

Mathematica

RealDigits[(26*Pi/3 - 14 + 2*Sqrt[2] - 4*Sqrt[3] + 10*Sqrt[5] - 2*Sqrt[6] + 26*Log[2] - 2*Log[5] + 10*Log[Sqrt[2] + 1] + 20*Log[Sqrt[3] + 1] - 35*Log[Sqrt[5] + 1] + 6*Log[Sqrt[6] + 1] - 2*Log[Sqrt[6] + 4] - 22*ArcTan[2*Sqrt[6]])/3, 10, 100][[1]]

Crossrefs

Cf. A070058, A336274, A353769, A353770.

Sequence in context: A275967 A155799 A021112 * A248318 A298852 A093066

Adjacent sequences: A353404 A353405 A353406 * A353408 A353409 A353410

Keyword

nonn,cons

Author

Amiram Eldar, May 07 2022

Status

approved