Which country has coastlines along both the Caribbean Sea and the Pacific Ocean?
Columbia
Tsunamis (and also underground volcano eruptions)<span />
-- To increase the frictional force between the two surfaces, press them together
harder, or rough up the area of contact with sandpaper or dirt.
-- To decrease the frictional force between two surfaces, decrease the force
with which they press together, or smooth (polish) the area where their surfaces
contact, or make the area <em>seem</em> smoother by lubricating it with grease, oil, air,
or smooth leaves.
