freeCodeCamp/curriculum/challenges/ukrainian/02-javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/map-the-debris.md

id, title, challengeType, forumTopicId, dashedName

id	title	challengeType	forumTopicId	dashedName
af4afb223120f7348cdfc9fd	Мапа Debris	1	16021	map-the-debris

--description--

Згідно з третім законом Кеплера, орбітальний період T двох точкових мас, що обертаються навколо одна одної по круговій або еліптичній орбіті, є:

T = 2 \pi \sqrt{\frac{a^{3}}{\mu}}

• a is the orbit's semi-major axis
• μ = GM is the standard gravitational parameter
• G is the gravitational constant,
• M is the mass of the more massive body.

Return a new array that transforms the elements' average altitude into their orbital periods (in seconds).

The array will contain objects in the format {name: 'name', avgAlt: avgAlt}.

The values should be rounded to the nearest whole number. The body being orbited is Earth.

The radius of the earth is 6367.4447 kilometers, and the GM value of earth is 398600.4418 km³s^-2.

--hints--

orbitalPeriod([{name : "sputnik", avgAlt : 35873.5553}]) повинен повертати [{name: "sputnik", orbitalPeriod: 86400}].

assert.deepEqual(orbitalPeriod([{ name: 'sputnik', avgAlt: 35873.5553 }]), [
  { name: 'sputnik', orbitalPeriod: 86400 }
]);

orbitalPeriod([{name: "iss", avgAlt: 413.6}, {name: "hubble", avgAlt: 556.7}, {name: "moon", avgAlt: 378632.553}]) повинен повертати [{name : "iss", orbitalPeriod: 5557}, {name: "hubble", orbitalPeriod: 5734}, {name: "moon", orbitalPeriod: 2377399}].

assert.deepEqual(
  orbitalPeriod([
    { name: 'iss', avgAlt: 413.6 },
    { name: 'hubble', avgAlt: 556.7 },
    { name: 'moon', avgAlt: 378632.553 }
  ]),
  [
    { name: 'iss', orbitalPeriod: 5557 },
    { name: 'hubble', orbitalPeriod: 5734 },
    { name: 'moon', orbitalPeriod: 2377399 }
  ]
);

--seed--

--seed-contents--

function orbitalPeriod(arr) {
  const GM = 398600.4418;
  const earthRadius = 6367.4447;
  return arr;
}

orbitalPeriod([{name : "sputnik", avgAlt : 35873.5553}]);

--solutions--

function orbitalPeriod(arr) {
  const GM = 398600.4418;
  const earthRadius = 6367.4447;
  const TAU = 2 * Math.PI;
  return arr.map(function(obj) {
    return {
      name: obj.name,
      orbitalPeriod: Math.round(TAU * Math.sqrt(Math.pow(obj.avgAlt+earthRadius, 3)/GM))
    };
  });
}