If you're not sure what all this stuff means, you can use Body:setMassFromShapes after adding shapes instead.
The first two parameters will be the local coordinates of the Body's center of mass.
The third parameter is the mass, in kilograms.
The last parameter is the rotational inertia.
x | number | The x-component of the center of mass in local coordinates. |
y | number | The y-component of the center of mass in local coordinates. |
m | number | The mass, in kilograms. |
i | number | The rotational inertia, in kilograms per squared meter. |