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.
Sunset over Mexico Beach pier from the dunes. As of the census of 2010, there were 1,072 people, 563 households, and 320 families residing in the city. The population density was 595.6 inhabitants per square mile (233.0/kmÂ²). There were 1,852 housing units at an average density of 1,028.9 per square mile (402.6/kmÂ²).