# A fun math problem.

Here is a fun math problem for you to solve.

You have a flash light that shines a circle on the wall with radius R you move back X units and it shines on the wall with a radius of R2. What is the angle of spread of the light θ?

The answer is 4.

I hope your joking.

Yeah sorry I’m not very into calculating things. I just kinda suck at it.

Is 4 even close?

I didn’t give any units so it would be given as an equation not a number.

See what I’m saying? Now I’ll wait patiently and check back for the answer.

Aren’t you going to have to specify an origin “X0” distance in order to solve that?

θ=arctan((R2-R)/X)

nope

yep except it would be 2 times for the full spread.

Ahhh… right… didn’t wake up before thinking about that one…

ΔX => ΔR

I’ve got one for you, Abstract;

Given a totally pure substance with a maximum propagation velocity of 1, what is the maximum change rate at any one point within the substance?

maximum propagation velocity? as in it is expanding at a velocity of 1?

Velocity implies a linear travel; distance/time.

I don’t follow what you are asking then maximum change rate of what in the substance?

would it be the speed of light?

2

Maximum change rate at any one point.

And no. It is speculated (or in some cases defined) that the “speed of light” is that maximum propagation velocity. But that isn’t the question. Assuming that there is a maximum propagation velocity (of anything really), how would you determine what the maximum amount of change at any one point in space must be? It is purely a mathematics issue.

…emm… no… unless you can defend that somehow.

Actually I have no idea what you are talking about but I figure the answer must be one of 4, 2, 1, 1/2 or 1/4.

Since 4 was already proposed in this thread and it was wrong, I picked the next number in the list : 2.

I will say that it is a particular number, although considering how often and easily I screw up my math due to absent mindedness, I might have that number wrong. Logic requires a specific number rationally accepting a 3D geometry.

Ist clue: “Every point is surrounded by a sphere.

I still don’t think i understand the question…