Momentum is not conserved if there is friction, gravity, or net force (net force just means the total amount of force). What it means is that if you act on an object, its momentum will change. This should be obvious, since you are adding to or taking away from the object's velocity and therefore changing its momentum.
Somerville, Massachusetts. Somerville (/ËsÊmÉrvÉªl/ SUM-Ér-vil) is a city located directly to the northwest of Boston, in Middlesex County, Massachusetts, United States. As of 2010, the United States Census has the city with a total population of 75,754 people, and is the most densely populated municipality in New England.
Massachusetts had an estimated 2009 population of 6,593,587. As of 2007, Massachusetts is estimated to be the third most densely populated U.S. state, with 822.7 per square mile, after New Jersey and Rhode Island, and ahead of Connecticut and Maryland. Massachusetts has seen both population increases and decreases in recent years. For example, while some Bay Staters are leaving, others including European, Asian, Hispanic and African immigrants, arrive to replace them. Massachusetts in 2004 included 881,400 foreign-born residents.