You have two coins of the same size and roll one around the other.

How many times does the rolling coin roll around its center?

Hint: It’s not one!

What if the coins were different sizes?

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# Rolling coins

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9 thoughts on “Rolling coins”

You have two coins of the same size and roll one around the other.

How many times does the rolling coin roll around its center?

Hint: It’s not one!

What if the coins were different sizes?

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Sakuratwice ðŸ™‚

piotrmilI believe it is called Copernicus’ theorem, or some variation of it.

Gnaneshwarit’s 2 revolutions…..for diff size the ans will be r1/r2+1…..where r1 and r2 are radius of static and rotating circles respectively.

samanthaumm 2 i gess i am dumb lol ðŸ™‚ LOL ON ME HAHAHAHAHAHAAHAHAHHAHAHHAHAHAHAHAHHAHAHAHAHAHAHAHAHHahahahahahahahhahshhhhahahahahahahahahahahahahahahah

MgbuFirst I think was Pi, but is impossible to do a GIF of that! ðŸ˜†

HassanThis is pretty easy. Answer is 1.5

Because when the outer coin roles, it makes a bigger circle outside with diameter of 2*r1+r2 or 3*r1 if they are equal size. The circumference of bigger circle will be 2*pi*(3*r1/2) and for outer coin we have 2*pi*r1 . If we divide these two we get the answer which is 1.5

KamptrollZero!!! It is rolling around the OTHER coin’s center!! :]

online scienceVisually it seems one to me!

Mathematically it is very very very confusing.

Henry BrownBefore I answer, does the coin have a milled or a plain edge Coin Terminology ? ðŸ˜ˆ as this may affect the roll