For example in case of explosion of a particle into many fragments momentum is conserved in the x direction but not in the y direction where gravity is acting but if we consider the particle and Earth as a system the gravity force becomes an internal force and hence momentum is conserved for that system.
Compared to the rest of the country, Soldotna's cost of living is 26.90% Higher than the U.S. average. As of 2014, Soldotna's population is 4,209 people. Since 2000, it has had a population growth of 11.91 percent. Average Commute time is 15 minutes.
The 23,000-square-mile (60,000 km2) Matanuska-Susitna Borough (the Alaskan equivalent of a county) governs the Mat-Su Valley. According to the 2010 Census, the borough's population is 88,995, a 50% increase since 2000. The Mat-Su Valley was originally inhabited by Athabaskan people and was explored by Russians in 1818.