{"id":203,"date":"2018-12-06T17:03:34","date_gmt":"2018-12-06T11:33:34","guid":{"rendered":"http:\/\/www.physicsacademyonline.com\/blog\/?p=203"},"modified":"2021-02-25T14:03:45","modified_gmt":"2021-02-25T08:33:45","slug":"tips-to-solve-physics-jee-advanced-2018-questions-ii","status":"publish","type":"post","link":"https:\/\/www.physicsacademyonline.com\/blog\/jee-advanced-preparation\/tips-to-solve-physics-jee-advanced-2018-questions-ii.html","title":{"rendered":"Tips to Solve Physics JEE (Advanced) 2018 Questions – II"},"content":{"rendered":"

Let Us<\/del> <\/em><\/i>YOU<\/span> Solve Physics JEE (Advanced 2018) Questions:<\/i><\/h3>\n

As you will recall, we plan to demonstrate here in a series of blogs, how a combination of sound theoretical knowledge and sharp problem-solving skill can ensure your success in any Board or Competitive Examination. We continue with JEE (Advanced) 2018, Paper-1, earlier known as IIT-JEE, held on 20 May 2018. There must be a large number of websites and printed books which dish out solutions to such question papers every year with unfailing regularity. But how much does a student benefit by passively memorising the steps of a solution done by somebody else? Not much, really. A student, with serious aspiration for success in an exam, must put themselves in the position of an examinee. They must test their own skill in quickly connecting a question to the relevant theories and formulas, and in applying them in proper order without errors. So we are here to let YOU solve the questions and problems, with minimal guidance from our end. That will make the desired difference in your preparation. Having said that, you must check your answers from our video solutions given along with.<\/p>\n

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Returning to Section 2 of Paper-1, there are eight problems in it. Each problem’s answer is a numerical value without unit (unit, if any, is already mentioned in the question). The correct numerical value has to be reported up to the second decimal place, after rounding off if necessary. There is no partial marking: full three marks for correct answer, zero marks otherwise.<\/p>\n

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Question 7<\/u>:\u00a0\u00a0 Two vectors A<\/strong> and B<\/strong> are defined as: A<\/strong> = ai\u00a0 <\/strong>and B<\/strong> = a (cos\u03c9<\/i>t i<\/strong> + sin\u03c9<\/i>t j<\/strong>), where a is a constant and \u03c9<\/i> = \u03c0<\/i>\/6 rad\/s. If \u2502A<\/strong> + B<\/strong>\u2502=\u00a0 \u00a0\u221a<\/span>3 .\u2502A<\/strong> – B<\/strong>\u2502 at time t = \u03c4<\/i> \u00a0for the first time, the value of \u03c4<\/i> \u00a0in second is\u00a0\u00a0 ______________ .<\/p>\n

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This problem involves Vectors, an introductory chapter in Physics, and a bit of Trigonometry. A vector can be expressed either as magnitude-and-direction or in unit-vector notation, which is the case here. How to add up or subtract two vectors expressed in terms of i<\/strong>, j<\/strong> (and k <\/strong>)? Subscribe to\u00a0 www.physicsacademyonline.com<\/a>, and watch this lecture: Chapter Name \u2013 Mechanics; Category \u2013\u00a0 Basic; Topic Name \u2013 Vectors; Video Name \u2013 Resolution of a Position Vector in Space.<\/span><\/i><\/p>\n

Hence find A<\/strong> + B<\/strong> and\u00a0 A<\/strong> – B<\/strong>. How to find the magnitude (denoted by modulus sign \u2502\u2502) of a vector expressed in terms of unit vectors? The same lecture mentioned above will be useful.<\/p>\n

Hence find \u2502A<\/strong> + B<\/strong>\u2502 and \u2502A<\/strong> – B<\/strong>\u2502 . Use the condition stated in the problem to get a trigonometric equation (involving sub- multiple angles). Solve for t (general solution of trigonometric equations). From a series of possible values of t, pick the smallest value t <\/em>.<\/p>\n

Only when you have completed<\/em>, confirm your answer from our MP4 video solution below.<\/p>\n