Revert "Completed physics related classes (untested)"

This reverts commit 9f48779388f724ca27ac404c5f5c4205b3fec4b1.
Revert "Revert "Completed physics related classes (untested)""

This reverts commit c21f28c346747d20fc9b6a9dd8cfac00f0470fe2.
Completed physics related stuff