Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °
You are not logged in.
Post a reply
Topic review (newest first)
Hello Bob , I think I made a mess of the graph plotting . I not able to plot it correctly . If there is assistance you can give , that will be wonderful .
OK. The centre of the dish is at (0,0). The x axis runs out towards the focus. The y axis is at right angles to this.
where the focus is at (a,0)
You want a diameter of 4.7 m That means the radius (distance from the x axis) is 2.35 m
And you want a = 1.8 m
So the depth of the dish will be
To make a card former for points on the surface of the dish, you need to plot the graph
If you compute y for a set of values of x using this:
you will get the top half of the curve.
You could calculate coordinates using a calculator and plot the graph, or maybe, use a graph plotter. There are plenty available on the net.
Good luck ... let me know how it goes.
Hello Bob , many thanks for all your efforts . My dish is 4.7 meter , focal point is 1.8 meter please help me get the dept of the dish . I will also like if possible to make a curve I can use to make the plate of the dish
So far I've just worked in two dimensions. The parabolic reflector for a dish is made by rotating the curve around the x axis in a circle.
For your measurements (make sure you convert cm to m) a = 1.52
My second diagram shows a point with y coordinate 2. This is because you gave the diameter as 4m so the radius will be 2.
which I make 0.65789. So I've rounded up to 0.658.
For your new dish you will have y = 2.35. You can choose an x and hence find a or the other way round.
Good luck with the build.
Some info at bottom of this page also: Parabola
Bob , many thanks , I wait for your reply soon . Umunna
OK, thanks for the additional data. I'm in the middle of some woodwork at the moment and only stopped for a coffee. I'll work out a formula later today. (My time 11.45 now)
Hello Bob, thanks for your explanations , I have presently a 4 meter in diameter with the following statistics , dept 65cm , and focal point of 152cm.
Post in help me section
I am trying to make a parabolic satellite dish of 4.7 meter size . Can any one please help with the formula .