A block is pulled along a surface at a constant velocity by a force of 200 N. Find the force of friction opposing the movement

Asimply means that over time there was some sort of change.

What is created when solids,liquids,an gases mix with one another

Imagine you are standing in the antarctic during the southern hemisphere summer. the sky is clear and blue. there are no clouds in the sky. your shadow is cast on the icy ground. what is the color of the shadow?