This is technically homework, but not for a grade, since this isn't for a class. This is purely so I can learn for personal interest.
I'm reading a basic physics book. I am at the part where it's talking about circular motion. One example question in it asks: If you attached a string to a rock, and whirled it around in a circle, then the string broke (let's say in a counter-clockwise direction, and the string broke at the number 3), what direction would the rock go? The possibilities are: straight out from the 3, or it would continue moving in a straight line upward if seen from an overhead view.
Well, I've done that a lot, and when I release something, it always goes straight out, so I chose straight out. But it says the correct answer is it will continue moving upward (if seen from above, it would appear to be up) and perpendicular to a line from the point the string broke to the center of the circle, so it would appear to be going straight up from the number 3 on a flat clock.
My question is why? When I twirl something around and let go of it, it flies straight out and away from me in a straight line. My idea is that momentum is carrying the object away in a straight line, but that the string is keeping it an equal distance away from me at every point along the circle, until the string no longer holds it, and that as long as the string is holding it, it is moving in a circular motion.
Can someone please explain why the book says the correct answer is that (if viewed from above, looking down at the flat 2D plane) the rock would appear to go up in a straight line from the number 3 where the string broke (assuming a counter-clockwise motion)?