Just to tease your minds, I propose this question. The earth is rotating, right? Centripital motion is provided by gravity. Objects undergoing circular motion tend to travel in a tangental trajectory relative to the circle they are released from. If we say the earth is still, and the universe is moving around it(using frames of reference), then how come if gravity suddenly went away, we would still fly off? This not only pertains to the earth but any other object, where the example of gravity which i used can be replaced by any other center-seeking force, such as tension. PS, I already know the answer, i just want to see who else knows it too.