Kinematics and Dynamics Kinematics and Dynamics Physics Help Forum Jul 13th 2018, 08:33 AM #1 Junior Member   Join Date: Jul 2018 Posts: 17 The angle between P and Q? The resultant R of vectors P and Q is perpendicular to P and R=P both, then the angle between P and Q is what? Now, what is the concept behind it? Could you provide me with an image of the resultant perpendicular to two vectors so that I can understand the concept and start solving the problem?   Jul 13th 2018, 09:29 AM #2 Physics Team   Join Date: Jun 2010 Location: Morristown, NJ USA Posts: 2,347 Please clarify what you mean by the phrase "R=P both" - are you trying to say that the magnitude of vector R = the magnitude of vector P? Keep in mind that for vector R (which is the sum of vectors P and Q) to be perpendicular to P, the vector Q must have a component in the negative P direction that is equal in magnitude to the magnitude of P, and Q must also have a component that is perpendicular to P. topsquark and Indranil like this.   Jul 13th 2018, 09:56 AM   #3
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Posts: 17 Please clarify what you mean by the phrase "R=P both" - are you trying to say that the magnitude of vector R = the magnitude of vector P? Keep in mind that for vector R (which is the sum of vectors P and Q) to be perpendicular to P, the vector Q must have a component in the negative P direction that is equal in magnitude to the magnitude of P, and Q must also have a component that is perpendicular to P.
Could you please get your points a little bit easier with a diagram so that I can understand the concept well?   Jul 13th 2018, 10:36 AM #4 Senior Member   Join Date: Apr 2015 Location: Somerset, England Posts: 1,035 Go back to you original definition of vector addition by the parallelogram law. Start by drawing vector P. From the same origin O, draw vector R the same length and at right angles to P. This will be the diagonal resultant of your parallelogram. Join the ends of the vectors R and P, noting the angle alpha as shown. Complete the parallelogram by drawing the vector OQ parallel to RP. Thus you can find the angle required by simple geometry. I will leave it to ChipB use these diagrams to explain what he means by components if he wants. topsquark and Indranil like this. Last edited by studiot; Jul 13th 2018 at 03:18 PM. Reason: spelling   Jul 13th 2018, 09:40 PM   #5
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Posts: 17 Originally Posted by studiot Go back to you original definition of vector addition by the parallelogram law. Start by drawing vector P. From the same origin O, draw vector R the same length and at right angles to P. This will be the diagonal resultant of your parallelogram. Join the ends of the vectors R and P, noting the angle alpha as shown. Complete the parallelogram by drawing the vector OQ parallel to RP. Thus you can find the angle required by simple geometry. I will leave it to ChipB use these diagrams to explain what he means by components if he wants.
Thanks a lot. So kind of you.  Tags angle, vector or resultant Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Physics Forum Discussions Thread Thread Starter Forum Replies Last Post garvilsinghal Kinematics and Dynamics 2 Apr 28th 2013 08:41 AM krje1980 Waves and Sound 0 Oct 29th 2012 01:17 PM christina Kinematics and Dynamics 4 Oct 31st 2009 03:31 AM christina Kinematics and Dynamics 1 Sep 29th 2009 04:29 AM Air Light and Optics 4 May 13th 2008 05:07 AM 