Momentum is conserved in case of motion under gravity because a object is pulled by the earth and the earth of pulled by the object. The momentum terms of the object and earth cancel each other out as the object has small mass but high velocity and the earth has very high mass and very small velocity in the opposite direction of the velocity of the object.
Southwick, Massachusetts. Southwick is a town in Hampden County, Massachusetts, United States. The population was 9,502 at the 2010 census. It is part of the Springfield, Massachusetts Metropolitan Statistical Area.
Kennewick is located along the southwest bank of the Columbia River, opposite Pasco and just south of the confluence of the Columbia and Yakima rivers. The population was 73,917 at the 2010 census. April 1, 2012 estimates from the Washington State Office of Financial Management put the city's population at 75,160. The nearest commercial airport is the Tri-Cities Airport in Pasco, a regional commercial and private airport.