Klaynos Posted May 23, 2015 Posted May 23, 2015 I was wondering if it was angular velocity. Thanks for the clarification. I can't accept that the whole system is only the ball. It must be all that is within the circle that the ball turns. Who decides such matters? The universe? To the ball it doesn't matter what the force is acting on it only that there is a force. It could be a sting or gravity, it doesn't matter, it is an object being acted on by a force. The ball and string is a nice example as it or clear the string cannot apply an outward force. 2
swansont Posted May 23, 2015 Posted May 23, 2015 OK I have told you how the ball achieves its angular momentum so where does the tension in the string come from? The ball wants to move in a straight line, which would take it further from the origin. The tension arises because the string (ideally) does not stretch, and thus exerts a force. 1
studiot Posted May 23, 2015 Posted May 23, 2015 (edited) The ball wants to move in a straight line, which would take it further from the origin. The tension arises because the string (ideally) does not stretch, and thus exerts a force. I like this answer, short and sweet. +1 (And no maths involved. ) Edited May 23, 2015 by studiot
swansont Posted May 23, 2015 Posted May 23, 2015 I can't accept that the whole system is only the ball. Well, start accepting it. This is physics — you don't get to decide the rules. The system is the ball, and only the forces on the ball dictate its acceleration. If you don't follow the rules, you aren't doing physics. You are doing something else.
dimreepr Posted May 23, 2015 Posted May 23, 2015 (edited) I’m opening a book, if anyone’s interested? Evens on 500 replies, (in this thread) 3/1 for 600 replies 10/1 for 700 and 5/1 it gets closed at 550 +/- 3, 50/1 bar. Swansont, and others, I admire you’re endless/saintly patience in trying to educate; please keep it up, I have money on this now. Edited May 23, 2015 by dimreepr
swansont Posted May 23, 2015 Posted May 23, 2015 OK as I've conceded above that there is only one force on the ball and that is the centripetal force, let's cast our minds back to the sliding issue discussed during the week, No, we're done here. You (seemingly) have accepted the obvious. Other discussion has been split http://www.scienceforums.net/topic/89107-centrifugal-force-experiment/
physica Posted May 23, 2015 Posted May 23, 2015 sawnsont you deserve a medal. I can't believe how long it took for others to get a physics concept that is usually taught in high school.
studiot Posted May 23, 2015 Posted May 23, 2015 (edited) sawnsont you deserve a medal. You get a medal if you can tell me what the centripetal forces are when these cogs rotate. Edited May 23, 2015 by studiot
Robittybob1 Posted May 23, 2015 Posted May 23, 2015 You get a medal if you can tell me what the centripetal forces are when these cogs rotate. two£.jpg They won't rotate (odd number of cogs). - so nil centripetal forces.
imatfaal Posted May 24, 2015 Posted May 24, 2015 I’m opening a book, if anyone’s interested? Evens on 500 replies, (in this thread) 3/1 for 600 replies 10/1 for 700 and 5/1 it gets closed at 550 +/- 3, 50/1 bar. Swansont, and others, I admire you’re endless/saintly patience in trying to educate; please keep it up, I have money on this now. I will take that bet <500 at evens. ! Moderator Note Thread Locked - we have concluded there is no centrifugal force on the ball. We will allow other discussions on related topics - but we will not allow a rehash of this simple question which was never in any doubt to those willing to read a physics text. I am ambivalent as to whether this thread should have been allowed to continue as long as it was; however, reason has finally prevailed, N1L remains intact, and I suppose 485 posts have been justified. Any threads along the lines of "yeah, but there is obviously an outward force on the ball..." will probably be locked with a notice to read this one. Do not be averse to opening threads with questions, no matter how basic they may seem, but please think twice if you have already concluded that 500 years of science is wrong. H/T to Swansont for doggedly refusing to bend his knee to the forces of ignorance and misunderstanding - and thanks to his noble occasional companions along the road to enlightenment. 4
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