361
General Science / Re: What is centrifugal force?
« on: 15/08/2016 23:13:07 »
I never said it didn't exist! I'm a scientist, for heaven's sake, not a writer of science textbooks!
Centrifugal force is what separates liquids in a centrifuge. If there was only a centripetal force, the liquid would all rise out of the test tube and splash around in the middle of the machine. Centrifugal force is what keeps "wall of death" riders stuck to the inside of the cage instead of collapsing in a heap at the bottom. Whan yo black out in a high-g turn, is it because your head is being pulled into the middle of the turn, or because your blood is being squeezed outwards? Does the centripetal force shrink the wheel, or does the centrifugal force expand the tyre? It is the radial outward force on a body that follows a curved path.
If you whirl a stone around on a string, you can feel the outward tension in the string. It must be outward because a string can't push, any more than a liquid can pull.
Idiot textbook writers say "but if you cut the string, the stone moves at a tangent, not a radius, so there can't be a radial force". I say "if you cut the string, the stone is no longer constrained to move in a curved path, so Newton's first law applies - the body continues to move in a straight line, which is obviously the tangent at the point of cutting."
This is the kind of nonsense that pays philosphers' salaries, and should therefore be banned from polite conversation.
Centrifugal force is what separates liquids in a centrifuge. If there was only a centripetal force, the liquid would all rise out of the test tube and splash around in the middle of the machine. Centrifugal force is what keeps "wall of death" riders stuck to the inside of the cage instead of collapsing in a heap at the bottom. Whan yo black out in a high-g turn, is it because your head is being pulled into the middle of the turn, or because your blood is being squeezed outwards? Does the centripetal force shrink the wheel, or does the centrifugal force expand the tyre? It is the radial outward force on a body that follows a curved path.
If you whirl a stone around on a string, you can feel the outward tension in the string. It must be outward because a string can't push, any more than a liquid can pull.
Idiot textbook writers say "but if you cut the string, the stone moves at a tangent, not a radius, so there can't be a radial force". I say "if you cut the string, the stone is no longer constrained to move in a curved path, so Newton's first law applies - the body continues to move in a straight line, which is obviously the tangent at the point of cutting."
This is the kind of nonsense that pays philosphers' salaries, and should therefore be banned from polite conversation.
The following users thanked this post: jeffreyH