Reddit Daily Programmer - Gravitational Force

Function New-Planet
{
    param
    (
        [string]$Name,
        [int]$Density,
        [int]$Radius
    )

    $planet = New-Object -TypeName PSObject
    $planet | Add-Member -MemberType NoteProperty -Name Name -Value $Name
    $planet | Add-Member -MemberType NoteProperty -Name Density -Value $Density
    $planet | Add-Member -MemberType NoteProperty -Name Radius -Value $Radius
    $planet | Add-Member -MemberType NoteProperty -Name Volume -Value ((4/3)  * [math]::pi * [math]::pow($radius, 3))
    $planet | Add-Member -MemberType NoteProperty -Name Mass -Value ($planet.Volume * $planet.Density)

    $planet
}

Function Get-GravitationalForce
{
    param
    (
        [double]$G = 6.67E-11,
        [Parameter(Mandatory=$true)][double]$mass,
        [Parameter(Mandatory=$true, ValueFromPipeline=$true)][PSObject]$Planet
    )

    # Format the result of the equation with no more than 3 decimal places
    $gravitationalForce = "{0:N3}" -f
      ($G * (($mass * $Planet.Mass) / [math]::pow($Planet.Radius, 2)))

    Write-Output "$($Planet.Name): $gravitationalForce"
}

Function SolveForReddit
{
    param
    (
        $inputString
    )

    $lines = $inputString -split '[\r\n]'

    if($lines.Count -lt 3)
    {
        Write-Error "Must have at least 3 lines."
    }

    # Foreach planet line, split the inputs to create a new planet,
    # and feed that planet into the gravitational force function.
    $lines[2..$lines.Count] |
    % {
        $input = $_ -split ", "
        New-Planet -Name $input[0] -Radius $input[1] -Density $input[2] |
            % { Get-GravitationalForce -mass $lines[0] -Planet $_ }
      }
}