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    Can anyone help im stuck on q. 7 January 03..OCR btw

    7. A particle starts from rest at the point O and travels in a straight line until it comes to rest at the point A. Its Velocity vms-1, t seconds after leaving O is given by: v= 0.3t - 0.003t2<----(squared!)

    (i)Find the distance OA

    (ii) Show that for the motion from O to A, the maximum speed of the particle is 1.5 times its average speed.

    i can do sum of it but then i kinda get lost half way thru.....lol, anyhelp wud be appreciated, esp since i suck at mechanics!

    Thanx..
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    (Original post by zaaks786)
    Can anyone help im stuck on q. 7 January 03..OCR btw

    7. A particle starts from rest at the point O and travels in a straight line until it comes to rest at the point A. Its Velocity vms-1, t seconds after leaving O is given by: v= 0.3t - 0.003t2<----(squared!)

    (i)Find the distance OA

    (ii) Show that for the motion from O to A, the maximum speed of the particle is 1.5 times its average speed.

    i can do sum of it but then i kinda get lost half way thru.....lol, anyhelp wud be appreciated, esp since i suck at mechanics!

    Thanx..
    ok... this is what i'm doing for m2 though!!

    i) when particle is at rest:

    0 = t(0.3 - 0.003t)

    Therefore, it is at rest

    t = 0

    and

    0.3 - 0.003t = 0s
    t = 100s

    Next you must intergrate v= 0.3t - 0.003t2 using t = 0s and t = 100s the limits

    s = [0.3 x 1002 / 2 - 0.003 x 1003 / 3] - 0
    s = 1500 - 1000
    s = 500m

    ok... in order to find the maximum speed you need to differenciate

    max speed occurs when dx/dt = 0

    v = 0.3t - 0.003t2
    0 = 0.3 - 0.006t
    t = 0.3 / 0.006
    t = 50s

    v = 0.3(50) - 0.003(50)2
    v = 7.5 m/s

    Average speed = s / t
    = 500 / 100
    = 5 m/s

    Therefore,

    7.5 / 5 = 1.5

    I agree, that's a very hard question for m1!
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    I get the same.
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    i wrote a plus instead of a minus first though but managed to correct it before you checked it... took me ages to figure out that the problem was just 1 sign though!
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    Here's the rest.
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    this is m2 Edexcel... wonder why it's m1 OCR
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    This is OCR m1?? :eek:

    *Comes one step closer to failing mechanics*
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    thanx u guys
    thts brill!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!
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    Does anyone have any OCR M1 past papers? Please PM me if you do.

    Thanks
    Jono
 
 
 
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