Explain how waves move through water if you drop a pebble into the water.

When that pebble is dropped in the pond, it pushes water out of the way. The water has nowhere to go but to the side and up, creating a circular peak around the drop point. This peak falls again, under the forces of gravity and surface tension, pushing the water beneath it out of the way.

d) physical means can be used to separate the components of air.

the components of a vector are the parts of the vectors that are to each other.

b perpendicular