Re: What would happen when if the Sun just Disappeared?

You are right in thinking of this question in terms of inertia, the
tendency of an object to remain in uniform (i.e. constant speed, straight
line) motion unless it is acted upon by an external force.  If the Sun were
to disappear suddenly (not that I can imagine a physical means by which
that might happen), the gravitational force it exerts on the Earth and the
other planets would disappear, as well.  Each of the planets would fly off
in straight lines, tangent to their old orbits, with the speeds they had
when they were orbiting.  Each planet would also continue to spin about its
own axis.  People and objects would still be held to the Earth by the
Earth's gravity.  That gravity has nothing to do with the Earth's axial
spin, however.  In fact, the axial spin slightly _decreases_ the effective
downward force felt by people and things at the surface of the Earth.  So,
if the Sun were magically to disappear, the Earth would continue moving,
but in a straight line rather than a circle.  The really alarming change
would be the devastating loss of energy - no Sun warming the planet would
have catastrophic consequences for life (not just human, but all life) on
Earth.  That's why I am glad that I can think of no way in which your
scenario could come about!

To read more about inertia and orbital mechanics, you can look at any intro
physics text.  The one I have used is "College Physics, 5th Edition" by
Franklin Miller, Jr.

[note added by MadSci Admin:  Using our search engine search
on the text string "rotate gravity earth" to read some
answers we have concerning how much less we weigh because
the earth is spinning!]