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Thread: Mechanics MC help

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    Mechanics MC help

    http://prntscr.com/ftv4dg

    Answer is C, any help appreciated.
    2016 HSC (Accelerated)
    // 2 Unit Maths // Studies of Religion 1 //

    2017 HSC
    // Biology // Physics // Maths Extension 1 // Maths Extension 2 // English Advanced //

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    Re: Mechanics MC help

    Quote Originally Posted by pikachu975 View Post
    http://prntscr.com/ftv4dg

    Answer is C, any help appreciated.
    Quick answer: C is the only option with the right units (or dimensions), so it's the answer.

    (As we know, the dimensions of angular velocity are inverse time (units of which is s-1); units of option C is ((m s-2)/m)1/2 = s-1. It is quick to check that none of the other options have the right units for angular velocity (and so cannot be correct). The first two (A and B) are dimensionless, as they just involve the ratio of two lengths. The last option is the inverse of C, so the units are s, which is wrong.)
    Last edited by InteGrand; 10 Jul 2017 at 11:57 PM.
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    Re: Mechanics MC help

    Quote Originally Posted by InteGrand View Post
    Quick answer: C is the only option with the right units (or dimensions), so it's the answer.

    (As we know, the dimensions of angular velocity are inverse time (units of which is s-1); units of option C is ((m s-2)/m)1/2 = s-1. It is quick to check that none of the other options have the right units for angular velocity (and so cannot be correct). The first two (A and B) are dimensionless, as they just involve the ratio of two lengths. The last option is the inverse of C, so the units are s, which is wrong.)
    Thanks heaps! Didn't realise radians per second was the same as s^-1. Also is there a method to doing it if this was a short answer?
    2016 HSC (Accelerated)
    // 2 Unit Maths // Studies of Religion 1 //

    2017 HSC
    // Biology // Physics // Maths Extension 1 // Maths Extension 2 // English Advanced //

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    Re: Mechanics MC help

    Quote Originally Posted by pikachu975 View Post
    Thanks heaps! Didn't realise radians per second was the same as s^-1. Also is there a method to doing it if this was a short answer?










    Last edited by InteGrand; 11 Jul 2017 at 7:58 AM.
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    Re: Mechanics MC help

    Quote Originally Posted by InteGrand View Post










    Thanks, didn't know we were allowed to use horizontal forces because the question was like "taking into account only tension and gravity"
    2016 HSC (Accelerated)
    // 2 Unit Maths // Studies of Religion 1 //

    2017 HSC
    // Biology // Physics // Maths Extension 1 // Maths Extension 2 // English Advanced //

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