Comments for Physically Incorrect http://www.physicallyincorrect.com The Deductions of a Physicist Fri, 19 Mar 2010 06:16:52 +0000 http://wordpress.org/?v=2.7 hourly 1 Comment on Physics Puzzle: A Trick with a Yo-yo by Converter http://www.physicallyincorrect.com/2009/07/physics-puzzle-a-trick-with-a-yo-yo/comment-page-1/#comment-9234 Converter Thu, 18 Mar 2010 12:07:19 +0000 http://www.physicallyincorrect.com/?p=807#comment-9234 if yo-yo is slipping then its acceleration a = Fcos theta/m if yo-yo is slipping then its acceleration a = Fcos theta/m

]]> Comment on About this Blog by Mario http://www.physicallyincorrect.com/about-this-blog/comment-page-1/#comment-8711 Mario Wed, 24 Feb 2010 01:13:56 +0000 http://www.physicallyincorrect.com/?page_id=45#comment-8711 I followed your explanation on neural networks i would like to know when are you going to continue with the material or if you could recomendme an undergraduate-level text on implementing neural networks using linear algebra. thanks I followed your explanation on neural networks i would like to know when are you going to continue with the material or if you could recomendme an undergraduate-level text on implementing neural networks using linear algebra. thanks

]]> Comment on Physics Puzzle: is Rolling Possible? by Correction http://www.physicallyincorrect.com/2009/02/physics-puzzle-is-rolling-possible/comment-page-1/#comment-8502 Correction Sun, 14 Feb 2010 13:20:21 +0000 http://www.physicallyincorrect.com/?p=164#comment-8502 "Since the sphere rolls without slipping, there cannot be any external forces acting on it." It is a wrong sentence. If an object rolls without slipping in a horizontal plane and unless you apply a force on it, there is no force of friction. The basic idea is that the acceleration of the contact point has to be zero in rolling without slipping with respect to an outside observer. Therefore, “It is impossible for a sphere to roll on a plane.” is invalid! “Since the sphere rolls without slipping, there cannot be any external forces acting on it.” It is a wrong sentence. If an object rolls without slipping in a horizontal plane and unless you apply a force on it, there is no force of friction. The basic idea is that the acceleration of the contact point has to be zero in rolling without slipping with respect to an outside observer. Therefore, “It is impossible for a sphere to roll on a plane.” is invalid!

]]> Comment on Physics Puzzle: is Rolling Possible? by A reasanable explanation http://www.physicallyincorrect.com/2009/02/physics-puzzle-is-rolling-possible/comment-page-1/#comment-8488 A reasanable explanation Sun, 14 Feb 2010 02:33:40 +0000 http://www.physicallyincorrect.com/?p=164#comment-8488 This proof is completely incorrect. Since the sphere rolls without slipping, there cannot be any external forces acting on it. In the above statement, there is a force of friction exerting on the sphere. It means that, when we assume the spere as if it were a point particle, it constantly slows down because of force of friction. And after some time, it stops. Because of the fact that rolling without slipping is continuous motion, there cannot be such a situation mentioned above. Furthermore, another aspect is that, when we consider the contact point, we can see that there is acceleration toward left and that's all! We need at least a force which can cause an acceleration toward right such that the sphere is able to roll without slipping. As you probably know, in rolling without slipping, the acceleration of the contact point has to be zero. This proof is completely incorrect. Since the sphere rolls without slipping, there cannot be any external forces acting on it. In the above statement, there is a force of friction exerting on the sphere. It means that, when we assume the spere as if it were a point particle, it constantly slows down because of force of friction. And after some time, it stops. Because of the fact that rolling without slipping is continuous motion, there cannot be such a situation mentioned above. Furthermore, another aspect is that, when we consider the contact point, we can see that there is acceleration toward left and that’s all! We need at least a force which can cause an acceleration toward right such that the sphere is able to roll without slipping. As you probably know, in rolling without slipping, the acceleration of the contact point has to be zero.

]]> Comment on Physics Puzzle: Gas Pressure by haram http://www.physicallyincorrect.com/2008/04/physics-puzzle-gas-pressure/comment-page-1/#comment-8349 haram Fri, 05 Feb 2010 14:14:38 +0000 http://www.physicallyincorrect.com/2008/04/physics-puzzle-gas-pressure/#comment-8349 the answer is T2>T1 the answer is T2>T1

]]> Comment on The Ice, Water and Oil Riddle by haram http://www.physicallyincorrect.com/2007/11/the-ice-water-and-oil-riddle/comment-page-1/#comment-8348 haram Fri, 05 Feb 2010 14:07:34 +0000 http://www.physicallyincorrect.com/?p=41#comment-8348 betweenthem because the density of ice is low frm water betweenthem because the density of ice is low frm water

]]> Comment on Neural Networks Tutorial, Part #1 by sattar http://www.physicallyincorrect.com/2007/11/neural-networks-tutorial-part-1/comment-page-1/#comment-8282 sattar Tue, 02 Feb 2010 07:49:12 +0000 http://www.physicallyincorrect.com/?p=35#comment-8282 I am new beginner in matlab and i need help on nntool.If anybody can help me please write me to :chsatar@gmail.com I am new beginner in matlab and i need help on nntool.If anybody can help me please write me to :chsatar@gmail.com

]]> Comment on Physics Puzzle: A Trick with a Yo-yo by sid http://www.physicallyincorrect.com/2009/07/physics-puzzle-a-trick-with-a-yo-yo/comment-page-1/#comment-8160 sid Fri, 29 Jan 2010 10:56:08 +0000 http://www.physicallyincorrect.com/?p=807#comment-8160 Don't think it can roll at all without slipping. The force of the string (F.cos(theta)) is trying to pull the yo-yo to the right (which would result in a clockwise rotation.) However, the torque (Fr) is trying to force the yo yo to rotate in a counter-clockwise direction. When the force is great enough to overcome friction, the yo yo gets dragged along the ground without rotating (otherwise it just sits there). When the force stops, the yo yo should start to roll forward (continuing the rightward velocity). Don’t think it can roll at all without slipping. The force of the string (F.cos(theta)) is trying to pull the yo-yo to the right (which would result in a clockwise rotation.) However, the torque (Fr) is trying to force the yo yo to rotate in a counter-clockwise direction.

When the force is great enough to overcome friction, the yo yo gets dragged along the ground without rotating (otherwise it just sits there). When the force stops, the yo yo should start to roll forward (continuing the rightward velocity).

]]> Comment on More Blog Statistics by cross stitch http://www.physicallyincorrect.com/2009/07/more-blog-statistics/comment-page-1/#comment-8089 cross stitch Mon, 25 Jan 2010 15:51:35 +0000 http://www.physicallyincorrect.com/?p=792#comment-8089 <a href="http://www.crossstitchartware.com/" rel="nofollow">cross stitch</a> cross stitch

]]> Comment on Physics Puzzle: A Trick with a Yo-yo by Mike http://www.physicallyincorrect.com/2009/07/physics-puzzle-a-trick-with-a-yo-yo/comment-page-1/#comment-8077 Mike Mon, 25 Jan 2010 03:09:39 +0000 http://www.physicallyincorrect.com/?p=807#comment-8077 I understand the roll with or without slipping, but I think there is a specific coefficient that is related to all of the variables and not just 0 or 1. I understand the roll with or without slipping, but I think there is a specific coefficient that is related to all of the variables and not just 0 or 1.

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