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    (Original post by chrissypie666)
    Did anyone else run out of time? lol
    yep... i literally didnt even have time to write one word on the 6 marker and the last few questions... 1hr 15 is not enough for that paper :'( :'( :'(
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    (Original post by mbh16)
    what did everyone get for the boy and the plank one?
    I think I said he could get across without it tipping as the moment of the weight of the board was more than the moment of the boy at the end?

    (I remember doing the calculation and writing quite a bit for those few marks!)
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    (Original post by mbh16)
    what did everyone get for the boy and the plank one?
    I don't know but honestly i was secretly hoping that as he got past the rock, the plank would flick up and hit him in the head... i get violent when I'm stressed :')
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    (Original post by philo-jitsu)
    Was the projectile traveling fastest just before it hit the floor....and slowest at its highest point?
    Yes I got that! Another few marks gained!
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    (Original post by Sufyxyz)
    (a)Centre of mass is point where a single force can be applied with no turning effect.

    (b)196N or round to 200N

    (c) it can't support the boy. Took moments from the embankment
    oh no, i don't think i got the last two of that question
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    (Original post by mbh16)
    Did u take the moments around the rock? so it was 3.2m away from the cog and 0.8m away from the boy
    I dunno, it said in the q that the plank was uniform so its centre of mass was in the middle right?
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    At the highest point the vertical component velocity is zero, therefore the resultant velocity is minimum. At the lowest point the vertical component of velocity is max, therefore resultant velocity is max.
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    I took moments from the rock...said it can support him....why is this wrong?

    If im taking moment from the rock for it to tilit the resistive force from the start of the ditch has to be zero if jts on the point of tilting at the rock....the moment produced by the weight was 1.2×32g

    And the boys moment from the rock was 46g*0.8m

    The weights moment was more so it cant tip....so the boy could walk to the end
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    (Original post by davgen7)
    I dunno, it said in the q that the plank was uniform so its centre of mass was in the middle right?
    Yeah thats what i assumed
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    If you had taken moments about the rock, resolving with the guy being at the end of the plank and find out the reaction force between the ledge and the plank and prove it is >0 which means the plank didn't tilt
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    What did you guys draw for the VT graph at the end of the projectile motion questions?

    I drew a linear line with negative gradient that touches the x axis at TH and the linear line with positive gradient at TF. Not sure if it's right tho.
    I'm sure it said ignore air resistance throughout the question so that's why my lines were linear but not sure if that's still correct?
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    (Original post by Sufyxyz)
    (a)Centre of mass is point where a single force can be applied with no turning effect.

    (b)196N or round to 200N

    (c) it can't support the boy. Took moments from the embankment
    I don't think you should've took moments from the bank though because it wouldn't have told you whether theres a supporting force at the bank or not? hence whether it was tipping or not.
    I took moments about the rock and found there was still a supporting force on the plank by the bank so the boy could stand at the end
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    (Original post by philo-jitsu)
    I took moments from the rock...said it can support him....why is this wrong?

    If im taking moment from the rock for it to tilit the resistive force from the start of the ditch has to be zero if jts on the point of tilting at the rock....the moment produced by the weight was 1.2×32g

    And the boys moment from the rock was 46g*0.8m

    The weights moment was more so it cant tip....so the boy could walk to the end
    I took moments about the rock. Pretty sure that's correct method. He could stand without it tilting.


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    What do you guys reckon the grade boundaries will be like?
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    Hehheeheheh, I'm so ready to DIE
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    (Original post by philo-jitsu)
    I took moments from the rock...said it can support him....why is this wrong?

    If im taking moment from the rock for it to tilit the resistive force from the start of the ditch has to be zero if jts on the point of tilting at the rock....the moment produced by the weight was 1.2×32g

    And the boys moment from the rock was 46g*0.8m

    The weights moment was more so it cant tip....so the boy could walk to the end
    You have to multiply all the masses by 9.81, to make the weight force instead of the mass.

    At least, I think so...
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    (Original post by txnilxnur)
    I don't think you should've took moments from the bank though because it wouldn't have told you whether theres a supporting force at the bank or not? hence whether it was tipping or not.
    I took moments about the rock and found there was still a supporting force on the plank by the bank so the boy could stand at the end
    Yea same tis what i did
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    (Original post by philo-jitsu)
    I took moments from the rock...said it can support him....why is this wrong?

    If im taking moment from the rock for it to tilit the resistive force from the start of the ditch has to be zero if jts on the point of tilting at the rock....the moment produced by the weight was 1.2×32g

    And the boys moment from the rock was 46g*0.8m

    The weights moment was more so it cant tip....so the boy could walk to the end
    moment is force x distance so you had to multiply both masses by 9.81, but i basically did the same as you but multiplied the masses by 9.81
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    (Original post by McDerdactyl)
    same although i got a D last year ahahah we can start a drug empire together, i feel like thats a decent back up tbh

    haha yes ! ... I have a few hours on GTA experience of selling drugs so thats all I need aha !... No one will ever suspect the physics kids .... we just might start our own breaking bad ah !
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    (Original post by Nerrad)
    Yea same tis what i did
    seems like the general consensus for this q was that he could walk on it so hopefully its right. don't see why its wrong though to be fair
 
 
 
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