NEET AIPMT SOLVED PAPER SCREENING 2005

  • question_answer
                    A stone tied to the end of a string of 1 m long is whirled in a horizontal circle with a constant speed. If the stone makes 22 revolutions in 44 s, what is the magnitude and direction of acceleration of the stone?

    A)                                                                                                                                                                                            \[\frac{\pi }{2}\] \[m{{s}^{-2}}\]and direction along the radius towards the centre

    B)                 \[{{\pi }^{2}}\,m{{s}^{-2}}\]and direction along the radius away from centre

    C)                 \[{{\pi }^{2}}\,m{{s}^{-2}}\] and direction along the radius towards the centre

    D)                 \[{{\pi }^{2}}\,m{{s}^{-2}}\] and direction along the tangent to the circle

    Correct Answer: C

    Solution :

                    Since, speed is constant throughout the motion, so it is a uniform circular motion. Therefore, its radial acceleration                 \[a=r{{\omega }^{2}}\]                 \[=r{{\left( \frac{2\pi n}{t} \right)}^{2}}=r\times \frac{4{{\pi }^{2}}{{n}^{2}}}{{{t}^{2}}}\]                 \[=\frac{1\times 4\times {{\pi }^{2}}\times {{(22)}^{2}}}{{{(44)}^{2}}}\]                 \[={{\pi }^{2}}m/{{s}^{2}}\]                 This acceleration is directed along radius of circle.


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