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B Mechanics of a throwing sling

  1. Jul 22, 2017 #1
    Hey, im not sure if this should be posted somewhere else, if so if you could direct me it would be much appreciated. So my question is how would i find the rotational velocity of a sling and how i could use that to calculate the force of a projectile from said sling. Ive tried doing some research online but most of what ive read is way over my head so i was hoping someone here might be able to help me.

    Thanks for any and all help you guys provide.
     
  2. jcsd
  3. Jul 22, 2017 #2

    Nidum

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    I assume that you are talking about a real sling - that is two thongs and a pouch which are whirled around until one of the thongs is released and the projectile flies free ?

    The whirling speed is really determined by choice by the person using the sling . The speed picked up by the projectile is a simple function of the whirling speed and the effective length of the sling .

    The effective length of the sling is the length of the thongs plus some additional length from your arms .

    So how fast (rpm) can you whirl a sling and what is the effective length of your sling ?
     
    Last edited: Jul 22, 2017
  4. Jul 22, 2017 #3

    Nidum

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    Hint : For simplicity you can assume that the centre of rotation for the whirling is at you shoulder . Remember that your arms will most likely be bent .
     
  5. Jul 22, 2017 #4
    So how fast (rpm) can you whirl a sling and what is the effective length of your sling ?[/QUOTE]
    Sling would be 48in long and idek what rpm would be.. cant find an average anywhere online socichave no clue
     
  6. Jul 22, 2017 #5

    Nidum

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    How fast can you whirl your arms around ?
     
  7. Jul 22, 2017 #6
    Pretty fast, if youre asking for a number i couldnt tell you
     
  8. Jul 22, 2017 #7

    Nidum

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    Whirl you arm as fast as possible and count the number of rotations made in a minute or if you can't manage a complete minute try thirty seconds .
     
  9. Jul 22, 2017 #8
    100
     
  10. Jul 22, 2017 #9

    Nidum

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    So 100 turns in 1 minute or 100 rpm . Good .

    100/minute is 100/60 = 1.67 revs/second .

    The speed of the sling pouch as it goes around in a circle is given by 2 * pi * L * (revs/second) where L is the effective length of the sling .

    L= 48 inches but we'll convert that to metres for our calculations . So we'll use L = 1.2 metres .

    Do you want to try working out the pouch speed ?
     
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