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Physics Problem (Discussion)

vineetgupta_1991 saidThu, 11 Dec 2008 05:45:50 -0000 ( Link )

A pendulum has time period T for small oscillations.An obstacle is placed directly beneath the pivot,so that only the lowest one quarter of the string can follow the pendulum bob when it swings in the left of its resting position.the pendulum is released from the rest at a certain point A.The time taken by it to return to that point is? Plz explain it at the earliest.

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  1. karthikiit saidSun, 14 Dec 2008 12:41:23 -0000 ( Link )

    t/4 is the answer

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  2. nirajshah21 saidThu, 15 Jan 2009 07:21:02 -0000 ( Link )

    it is 3T/4. time period will change to t/2 when string length for oscillation is restricted to be l/4. in this case it will complete half the oscillation and again length will become l. so time for restricted part will be t/2/2 ==t/4 and for next part it will take t/2 so net time = t/2+t/4=> 3t/4.

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  3. nirajshah21 saidThu, 15 Jan 2009 07:28:24 -0000 ( Link )

    it is 3T/4. time period will change to t/2 when string length for oscillation is restricted to be l/4. in this case it will complete half the oscillation and again length will become l. so time for restricted part will be t/2/2 ==t/4 and for next part it will take t/2 so net time = t/2+t/4=> 3t/4.

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  4. vineetgupta_1991 saidThu, 15 Jan 2009 14:49:19 -0000 ( Link )

    Thanx

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  5. nitesh 1 saidMon, 26 Jan 2009 08:50:54 -0000 ( Link )

    i think 3T/4 is the right answer

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  6. Sureshbala saidSun, 08 Feb 2009 15:50:55 -0000 ( Link )

    The answer has to be 3T/4. When the string oscillates towards the right from the rest point the time to come back to the rest position will remain same which is T/2. Now when it swings to the left, since the length of the string is l/2, the time taken will be π\sqrt{\frac{\frac{l}{4}}{g}} = \frac{T}{4}

    Hence the total time taken to come back to the original position is 3T/4

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  7. nitin k saidTue, 24 Feb 2009 05:14:57 -0000 ( Link )

    it is 3t/4. the phasor travels with twice the angular velocity after the pendulum meets with the obstruction as the length has become one fourth the original length. go by this approach and u will do it with utmost ease!

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