What does it mean to say that momentum is conserved? when momentum or any other object in physics doesn't change..... momentum = momentum before and after the collision. Elastic collision
The 2016 Springfield, Illinois, population is 116,565. There are 1,955 people per square mile (population density). The median age is 38.7. The US median is 37.4. 44.11% of people in Springfield, Illinois, are married. 14.83% are divorced.
In 2000 the city population was 81,500, and 76,122 in 2010. Decatur is the sixth-most populous city in Illinois, outside of the Chicago Metropolitan Area. According to Sperling's Best Places, Decatur's metropolitan area population is 114,749.