1. What grade of pencil (lead)?
2. How hard are you pushing down?
3. How big of a circle?
4. Just HOW sharp of a pencil?
   

a) How sharp ?

b) What diameter circle ?

c) What grade of lead is your pencil ?

d) The line from a fixed diameter lead (e.g. 0.5mm) as used in draughting pencil, or mechanical pencil will be the same at the finish as the start.

What is the roughness of the surface?

What material ?

larger.

If you are drawing a circle continuous...would you ever be finished? If you stay on your line, it would be as thick as the lead in your pencil...until you ran out of pencil.

Drew

Hey you guys....chill a little. Drew K has the most logical answer so far. I think the real answer might be: It's as thick as you want it to be! But then again...how long is a piece of string? As Confusion Once Say... Man who live on side of hill is not on the level. Why oh why do people ask such difficult questions?

To be blunt......

By definition a circle is continuous, so if the circle is small the lead will still be fairly sharp. If it is a large circle, with more lead used it will be less sharp.

Now, if you were to continually draw circles......

You have to draw the line somewhere.

If you tilt the pencil a bit, and carefully rotate as you draw, you can obtain a trace of nearly zero and nearly uniform width, even without using a uniformly thin lead. Either a pen or pencil plotter can do even better, unless you're really good.

Pencil thin

It depends upon the quality of lead in the pencil...

So how's British Rail doing these days ?

It would be the same thickness as when you started, however it's width might increase
Del the smarty cat

Oh you have been using one of those carpenter's pencils

The question said "...after you finish...", so the correct answer is 0 since I would never finish; as soon as I get half-way round, to pi, I always stop and go get a cuppa to go with the pi.

how thick would the line be

And the answer is 0 (zero) -

I agree with TVP but not for the reason he said.

It is a line and the line one dimensional object in the co-ordinate (straight line in cartesian coordinate and circle in polar co-ordinate, for special co-ordinate systems it can be curved lines too but in all cases the thickness (ie the dimension in any of the axes perpendicular to the principal axis) will be zero.

Else it is not a line - it is an annulus .

Not quite. In the original post it says to draw a circle, then asks how thick the line would be. Thus setting the parameters for a polynomial line.

I do like TVP's but only for the cuppa....it has been years since I had a good cuppa of real British Tea.

Drew

OP is not a trick question.

it is approx. 120 atoms thick.