Fundamentally, momentum conservation is linked to invariance under space translations. See Noether's theorem. If you want to find a system that does not conserve momentum you should look for situations where space is not uniform, e.g. balls rolling on the surface of a bowl, a planetary system (when the dynamics of the sun is neglected), etc.
Socorro is a city in Socorro County in the U.S. state of New Mexico. It is in the Rio Grande Valley at an elevation of 4,579 feet (1,396 m). In 2012 the population was 8,906.
Sierra County, New Mexico (NM) County population in 2014: 11,325 (66% urban, 34% rural); it was 13,270 in 2000. County owner-occupied with a mortgage or a loan houses and condos in 2010: 1,819. County owner-occupied free and clear houses and condos in 2010: 2,463. County owner-occupied houses and condos in 2000: 4,571.