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    Droplets in a deodorant spray have a mass of about 4*10^-12 kg and a radius of about 0.1mm
    Estimate the terminal velocity of the droplets in air with a viscosity of 2 * 10^-5 Nsm^-2

    How do I do this?
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    There's a simple explaination here: http://alevelnotes.com/?id=113.
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    use stokes law http://en.wikipedia.org/wiki/Stokes'_law
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    what are the passwords
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    btw I used the formula on this website and the answer did not agree with that in my text book
    I got 3 * 10^-4

    What about you?
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    First of all, from the information given it follows that droplets are less dense than air. Is it surely correct?
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    I don't know for sure it is just a question from a past paper
    the answer is (according to mark scheme)
    about 1 mm/s
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    Taking the viscous force, upthrust and weight into account gives a terminal velocity of around 2.7x10^-4 m/s upwards.

    If you ignore upthrust, you get around 1 mm/s downwards. To be honest, I've got no clue why this should be the way to do it. Especially that upthrust is greater than weight in this case.
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    ok, thanks so much for that!!!!
 
 
 
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