Which of the following criteria do astronomers use to classify an object as a planet? orbits a star gravity makes spherical at least as large as mercury clears orbits of other objects

The correct answer is Orbits a star, gravity makes it spherical, and clears orbits of other objects. Planets can be smaller than mercury so it's not a criterium.

Velocity=total displacement/timefrom house to store is 500 from store to neighbor is 200 therefore total displacement=500+200=700metrestherefore,700metres/910seconds=0.8metres per second