What happens to the density of a gas when it is compressed

Diego kicks a soccer ball from the end line. his fellow students time and mark the soccer ball as it moves down the field. the graph represents the ball's progress. based on the graph, during what time is the velocity constant and positive?

The process of a material going through a change of state from a gas to a liquid

Which two statements are true about a system? a system is a group of objects analyzed as one unit. energy that moves across system boundaries is conserved there's only one way to define the boundaries of a system all systems are made by humans