Mathematical question (diameters)
Discussion
Anyone good at math(s) that can calculate a diameter at a given point?
I want to purchase some plastic plant pots to sit inside some terracotta pots on my patio, that way I can lift plants out when they die back and slot another pot inside containing different plants, maintaining the planting throughout the seasons.
With the plastic plant pot sketched below, because of the shape of the terracotta pots I'd like to know the diameter of the plastic plant pot at a certain point, being 20cm down from the top.
I guess I can calculate the diameter half way down the pot by calculating the difference between the top & bottom diameters, then halving that figure then adding it back on? But what about the diameter at any other given point?
Is there a formula I can use to get the same measurement with different sized pots where I have their measurements but wish to know the diameter at certain points down from the top?
So the pot I'm thinking of buying is..
320mm diameter at the top
235mm diameter at the base
260mm tall
I want to purchase some plastic plant pots to sit inside some terracotta pots on my patio, that way I can lift plants out when they die back and slot another pot inside containing different plants, maintaining the planting throughout the seasons.
With the plastic plant pot sketched below, because of the shape of the terracotta pots I'd like to know the diameter of the plastic plant pot at a certain point, being 20cm down from the top.
I guess I can calculate the diameter half way down the pot by calculating the difference between the top & bottom diameters, then halving that figure then adding it back on? But what about the diameter at any other given point?
Is there a formula I can use to get the same measurement with different sized pots where I have their measurements but wish to know the diameter at certain points down from the top?
So the pot I'm thinking of buying is..
320mm diameter at the top
235mm diameter at the base
260mm tall
Maths free method?
Two pieces of wood , length more than half the dia at the ledge. Span them across the ledge tight against each other. Put a line anywhere on the overlap across both.
Remove the sticks, reposition on a flat surface with your markings lined up. Measure the length of the sticks.
Two pieces of wood , length more than half the dia at the ledge. Span them across the ledge tight against each other. Put a line anywhere on the overlap across both.
Remove the sticks, reposition on a flat surface with your markings lined up. Measure the length of the sticks.
sospan said:
Maths free method?
Two pieces of wood , length more than half the dia at the ledge. Span them across the ledge tight against each other. Put a line anywhere on the overlap across both.
Remove the sticks, reposition on a flat surface with your markings lined up. Measure the length of the sticks.
He wants the outer diameter of the pot.Two pieces of wood , length more than half the dia at the ledge. Span them across the ledge tight against each other. Put a line anywhere on the overlap across both.
Remove the sticks, reposition on a flat surface with your markings lined up. Measure the length of the sticks.
JohnWest said:
At 260 deep, the diameter is 255mm - modelled on CAD
This is Pistonheads in full effect....A bloke needs to know whether his plant pots will fit inside one another.....within 30mins, someone (who could literally be sat on the other side of the world) has drawn the pots up, to scale, in CAD software to complete the analysis. Love it
Slow day in the office John?
I must say I am very disappointed with the responses. I was hoping for much head scratching and pages of bickering over the correct answer, with folk insulting each others intelligence and falling out with each other, and comments such as 'if you don't know the answer then perhaps you shouldn't be gardening' etc 
I've measured the diameter inside of the terracotta pots where the ledge is, and its 255mm, exactly the same as the plastic plant pots at the same point, so at least I know they will fit nicely. As for those who were able to calculate the correct answer, a big thank you and have you considered being a contestant on programmes such as Krypton Factor or Mastermind. If not you are underselling yourselves
And thank you to JohnWest for conducting your CAD experiment, and for the cans of divine tuna.
I've measured the diameter inside of the terracotta pots where the ledge is, and its 255mm, exactly the same as the plastic plant pots at the same point, so at least I know they will fit nicely. As for those who were able to calculate the correct answer, a big thank you and have you considered being a contestant on programmes such as Krypton Factor or Mastermind. If not you are underselling yourselves
And thank you to JohnWest for conducting your CAD experiment, and for the cans of divine tuna.
Edited by The Gauge on Thursday 9th May 14:16
I must say I am very disappointed with the responses. I was hoping for much head scratching and pages of bickering over the correct answer, with folk insulting each others intelligence and falling out with each other, and comments such as 'if you don't know the answer then perhaps you shouldn't be gardening' etc
pti said:
Give a man the answer, he'll survive for a few hours.
Teach a man the calculation and he'll still ask for the f
king answer...
Teach a man the calculation and he'll still ask for the f
king answer...GroundEffect said:
Username checks out.
This really isn't hard. It's not even GCSE level.
Seems I spoke too soonThis really isn't hard. It's not even GCSE level.
Edited by The Gauge on Thursday 9th May 16:41
RustyMX5 said:
If you're planning to take the plastic pots out if the plants die, are you taking the expansion of the plastic into account in the hot summer sun?
I'll be removing them when flowers (such as spring bulbs) have finished flowering, and elsewhere in the garden out of sight I'll be growing other plants in the pots to replace them, so will be rotating them through the year. I do this already but I've bought new terracotta pots so need to replace the plastic inner pots to fit.Good point about expansion though, but they should'nt be in contact with the inner walls of the terracotta pots other than maybe where the ledge is.
The Gauge said:
I've measured the diameter inside of the terracotta pots where the ledge is, and its 255mm, exactly the same as the plastic plant pots at the same point, so at least I know they will fit nicely.
The plastic pot should be pretty reliably the same, but I wouldn't rely on the terracotta pots always being spot-on, unless you can try before you buy. A bit of clearance would be handy.Sheepshanks said:
The plastic pot should be pretty reliably the same, but I wouldn't rely on the terracotta pots always being spot-on, unless you can try before you buy. A bit of clearance would be handy.
I've already bought the terracotta pots so the measurements are what I have taken. The plastic inner pots wont be as tall but I'll be standing them on bricks inside the terracotta pots.Gassing Station | Science! | Top of Page | What's New | My Stuff