Bill and Amy want to ride their bikes to the school which is 13.9 kilometers away. It takes Amy 45 minutes to arrive at the school and Bill arrives 15 minutes later. How much faster, in meters/second (m/s) is Amy's average speed?

that tool is called an altimeter which measures your altitude which can be used to tell which atmosphere you are currently in, including the stratosphere.

hope this ! : )

float.

archimedes' principle

denser than water sinks in water.

denser than mercury would sink in it