Hello,
A physical change describes a change that does physically and does not display “chemical” signs which are signs that indicate a precipitate being formed, change in color, density, or producing gas, etc. “Tearing a piece of paper in half” is a physical change because like I said earlier it doesn’t show any chemical change signs. I hope this helps you out!
The answer is studying how people use time.
Hope this helps!
Maybe because gravity has control of each formation of the solarsydtem thats why its just a guess
