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Volume calculation

  • 18-05-2009 10:00pm
    #1
    Orion
    Closed Accounts Posts: 12,807 ✭✭✭✭


    I measured on a raised bed in inches and worked out the volume of topsoil to be 2 cubic metres (had to convert because it's sold in this new-fangled metric crap :D. But then just as a double check I measures the whole thing out in cm and it works out as 1 cubic metre. My conversion is sound but I want to be certain as I have to order topsoil to fill it.

    Can someone have a look at the diagram below and tell me what the volume is. The only thing missing on the diagram is the depth which is 25cm (all measurements are in cm). The diagram isn't properly to scale - I'm no graphic artist as you can probably tell :)

    garden.png

    Thanks.


Comments

  • #2
    Thoie
    Registered Users, Registered Users 2 Posts: 6,344 ✭✭✭Thoie


    I got 0.9967401408 cubic metres if that helps?

    Maths attached in excel


  • #3
    hivizman
    Registered Users, Registered Users 2 Posts: 1,163 ✭✭✭hivizman


    The surface area of piece A is 107^2 - 1/2 x 55^2 (area of the square less the triangle cut out of it, which has sides of 107 - 52 = 55cm). This is 9,936.5 cm^2. The shorter rectangular piece has an area of 176 x 52 = 9,152 cm^2, and the longer rectangular piece has an area of 398 x 52 = 20,696 cm^2. Hence the total surface area is 39,784.5 cm^2. Given that the depth is 25 cm, the volume is 994,612.5 cm^3, which is approximately 1 cubic metre.

    Check the depth - 25cm or 10 inches seems a bit shallow for a raised bed. But it's better to order 1 cubic metre and have to reorder than to order 2 cubic metres and have twice the quantity you actually need.


  • #4
    Orion
    Closed Accounts Posts: 12,807 ✭✭✭✭Orion


    hivizman wrote: »
    Check the depth - 25cm or 10 inches seems a bit shallow for a raised bed. But it's better to order 1 cubic metre and have to reorder than to order 2 cubic metres and have twice the quantity you actually need.

    I'd worked it out as .995 m3 so we're all in agreement.

    It's actually not better to order less - soil is €12/m3 but delivery is €85. So I'd be better off ordering more than I need. I've plans for the back garden next so it wouldn't go to waste anyway. But you have made a very good point- I think in my initial inches calculation I reckoned on just under 2 feet depth - there's the difference in my two reckonings. So I'm not going mad :)

    Thanks to both of you.


  • #5
    Thoie
    Registered Users, Registered Users 2 Posts: 6,344 ✭✭✭Thoie


    Macros42 wrote: »
    I'd worked it out as .995 m3 so we're all in agreement.

    It's actually not better to order less - soil is €12/m3 but delivery is €85. So I'd be better off ordering more than I need. I've plans for the back garden next so it wouldn't go to waste anyway. But you have made a very good point- I think in my initial inches calculation I reckoned on just under 2 feet depth - there's the difference in my two reckonings. So I'm not going mad :)

    Thanks to both of you.

    If you hadn't already used Excel for the calcs, you can just switch the 25's for the new depth in mine :)


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