Advertisement
If you have a new account but are having problems posting or verifying your account, please email us on hello@boards.ie for help. Thanks :)
Hello all! Please ensure that you are posting a new thread or question in the appropriate forum. The Feedback forum is overwhelmed with questions that are having to be moved elsewhere. If you need help to verify your account contact hello@boards.ie

JC area and volume question help???

Options
  • 24-05-2013 1:28pm
    #1
    ronan74
    Registered Users Posts: 10 ✭


    This Q is from the project maths paper 2 sample paper E. It says "One third of the container (cylinder and hemisphere) is filled with water. Calculate the depth of water in the container". The volume of the original container is 648pi. The radius is 6cm and height of total shape is 20cm. Any ideas how to do this??? :confused:
    Tagged:


Comments

  • Options
    #2
    Jack_OLantern
    Registered Users Posts: 193 ✭✭Jack_OLantern


    Try using your log tables, use the volume formula for a cylinder and a hemisphere? Just guessing, but it's something like that. :pac:


  • Options
    #3
    Michael D Not Higgins
    Registered Users Posts: 7,223 ✭✭✭Michael D Not Higgins


    One third of the volume is 216Pi.
    If the hemisphere is on the bottom:
    Volume of hemisphere is (2/3)(Pi)R^3.
    R is 6, so volume is 144Pi.
    216Pi - 144Pi = 72Pi (the volume of water in the cylinder)
    Volume of cylinder is (Pi)(R^2)(h)
    Solving for h is 2cm
    Adding 6cm radius makes depth 8cm

    If the shape is the other way around, 216Pi is the volume in the cylinder only, which gives h as 6cm.


  • Options
    #4
    DublinArnie
    Closed Accounts Posts: 2,823 ✭✭✭DublinArnie


    Junior Cert is approxmently 11 days away ... and you can't answer a simple area and volume question? I wouldn't blame you :p Project Maths paper two is ****ed up! *rollseyes*


  • Options
    #5
    Jack_OLantern
    Registered Users Posts: 193 ✭✭Jack_OLantern


    DublinArnie wrote: »
    Junior Cert is approxmently 11 days away ... and you can't answer a simple area and volume question? I wouldn't blame you :p Project Maths paper two is ****ed up! *rollseyes*

    It's soooo bad!!! Everyone hates it. Half of it is way too easy like Stem and Leaf and probability and then the other half is practically impossible! Area and Volume isn't too bad but I can never get the last part, like when it's partly filled with water.


  • Options
    #6
    Cr4pSnip3r
    Registered Users Posts: 792 ✭✭✭Cr4pSnip3r


    Jack_OLantern wrote: »
    It's soooo bad!!! Everyone hates it. Half of it is way too easy like Stem and Leaf and probability and then the other half is practically impossible! Area and Volume isn't too bad but I can never get the last part, like when it's partly filled with water.

    Yes.


  • Advertisement
  • Options
    #7
    ronan74
    Registered Users Posts: 10 ✭ronan74


    Michael D Not Higgins wrote: »
    One third of the volume is 216Pi.
    If the hemisphere is on the bottom:
    Volume of hemisphere is (2/3)(Pi)R^3.
    R is 6, so volume is 144Pi.
    216Pi - 144Pi = 72Pi (the volume of water in the cylinder)
    Volume of cylinder is (Pi)(R^2)(h)
    Solving for h is 2cm
    Adding 6cm radius makes depth 8cm

    If the shape is the other way around, 216Pi is the volume in the cylinder only, which gives h as 6cm.

    Thank You!!!!! :):)


  • Options
    #8
    ronan74
    Registered Users Posts: 10 ✭ronan74


    DublinArnie wrote: »
    Junior Cert is approxmently 11 days away ... and you can't answer a simple area and volume question? I wouldn't blame you :p Project Maths paper two is ****ed up! *rollseyes*

    Most of its grand....but some of it just doesn't make sense , but I got an A in the pre's so Im hoping it'll be the same for the real thing :)


  • Options
    #9
    Jack_OLantern
    Registered Users Posts: 193 ✭✭Jack_OLantern


    ronan74 wrote: »
    Most of its grand....but some of it just doesn't make sense , but I got an A in the pre's so Im hoping it'll be the same for the real thing :)

    *Might* just want to revise area & volume 1st though!


Advertisement