The human does this level of organization relate to cells? to organ systems?

Which object is most likely represented by a dot?

Standing side by side ,you and a friend step off a bridge at different times and fall for 1.6s to the water below.your friend goes first,and you follow after he has dropped a distance of 2.0m.when your friend hits the water,is the seperation between the two of you 2.0m or more than 2.0m? verify your answer with a calculation.

What are similarities and differences between refraction, reflection, diffraction and absorption?