Julie finds a snail on the sidewalk and wants to know whether or not the snail moves throughout the day. She places a single mar
k on the sidewalk next to the snail. What will Julie use the mark for initially?
determining how fast the snail moves
acting as a standard unit of measure
determining the displacement of the snail
acting as a reference point for detecting motion
Mass number<span> is the </span>number<span> of protons </span>and<span> neutrons in an atom. </span>Atomic mass<span> is the average </span>mass<span> of all the isotopes of a certain type.</span>
