If the earth stopped rotating, would we really fly inertially at 1000mph? I heard this on Prof. Neil Tyson's StarTalk podcast (this episode) and had a question about it. In a Q&amp;A session, a listener had asked what would happen if Superman really did stop the earth from rotating and rotated it in the other direction. Prof. Tyson's response was that if the earth, which is rotating at approx. 1000mph about its axis, is stopped, everything that is not anchored on earth will move the opposite direction at 1000mph and we'd all go crashing into things at that speed.

I suppose that is just simple inertia: if a body moving at 1000mph is stopped abruptly, everything that was moving with it but not attached to it would indeed attempt to continue in the same direction at 1000mph. However, the earth is rotating rather than moving in a straight line. Essentially, gravity is strong enough to ensure that we are not thrown off into space by the centrifugal force from the earth's rotation (we aren't holding on to our dear lives as the earth turns at 1000mph). So in a sense, aren't we anchored to earth by gravity? And therefore, doesn't it mean that if the earth stopped abruptly, we'd just stop with it? (I'm thinking of say a centrifuge with test tubes attached to it. Though as I think about this, I feel that we'd sway at the point of attachment instead of stand still, were the earth to stop).

Can someone help resolve this for me?
You would be sliding, because the friction between you and Earth would be too weak, or else you wouldn't survive the acceleration, if the rotation of Earth would be changed abruptly. That's like crashing into a wall with several hundred mph. This is with the exception of close to the poles.

Your weight wouldn't change much. On a smooth, plane, and horizontal surface you would slide (due to your inertia). Your velocity you would be sliding depends on your geographic latitude. At the equator it would be at the maximum. At the poles it would be zero. More precisely the velocity would be proportional to the cosine of the latitude (latitude 0 at the equator, and (+/-) 90 degrees, resp. $\pi/2$ at the poles).

Even more precisely, the speed you would be sliding would be $$2\cdot 465.1~ m/s \cdot cos ~\varphi,$$ with $\varphi$ the latitude.
Factor two, because superman accelerates to the opposite direction. Earth's equatorial rotation velocity is $465.1~m/s$.