The Total Mementum Is Conserved

Newton's law says that force equals mass times acceleration. Another way to write newton's is the change in momentum. If you want to change something by a lot, it takes a big force. O a change something momentum by a little bit, i takes a smaller force instead. Something without a lot of momentum doesn't take much force to stop grind. We don't really know how this happens but we observe it and tell our own mathematical stories about it.