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/sci/ - Science & Math

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[ERROR] No.3708552 [Reply] [Original]

Okay /sci/ I am desperate and am hoping you all can assist me. I have a question for astronomy dealing with making an ellipse using a loop of string and two thumbtacks. The string is first stretched over the thumbtacks which act as foci. The string is then pulled tight using the pencil which can then trace out the ellipse.

Now the question is: Assume that you wish to draw an ellipse with a semi-major axis of a=20 cm and e = 0.5, Using what you have learned earlier in this lab, what would be the appropriate distances for a) the separation of the thumbtacks and b) the length of the string? Please fully explain how you determine these values.

I will be extremely grateful if you guys help :)

>> No.3708598

bumping since this is a fast board.

>> No.3708611

>>3708552
>/sci/
>fast
only when it's shit.

Also I have absolutely no idea, but I just thought I'd mention that we're shit.

>> No.3708824

The focal length <span class="math"> f [/spoiler] is the distance between the origin, and each of your thumbtacks (the focii). Use the formula <span class="math"> e = \frac f a [/spoiler] with the numbers you have to solve for <span class="math"> f [/spoiler]