What are three common clues that a chemical change has occurred

If an athlete runs once around a track, back to the starting line, her average velocity is zero. true or false?

Properties seen when one one substance changes to another are known as properties

Two trains leave a station at the same time, train a travels at a constant speed of 16 m/s. train b starts at 8.0 m/s but accelerates constantly at 1.0 m/s squared. after 10.0 seconds, which train has the greater speed?