Question

A penny has a thickness of approximately 1.0 mm. if you stacked Avogadro's number of pennies one on top of the other on Earth's surface, how far would the stack extend in km?

Any help is much appreciated!

Answer 1

`6.02*10^17km`

Explanation:

Well, that's a weird question...

Anyways, Avogadro's number is approximately equal to `6.02*10^23`.

That means, that if you stack a total of `6.02*10^23` pennies, its height would be a total of `6.02*10^23 mm`.

`1 mm = 1*10^-6km`

`:.6.02*10^23mm=6.02*10^23*1*10^-6km`

`6.02*10^23mm=6.02*10^17km`

It would extend approximately `6.02*10^17km` above the Earth's surface.

I wonder where will you get all those pennies from?

Answer 2

Well, this is something to make a meal of.....dimensionally....

Explanation:

Now `1*mm-=1xx10^-3*m`...agreed? Because the prefix `"milli"-=10^-3`. And so we gots Avogadro's number of pennies....we reach a height of...

`6.022xx10^23xx1xx10^-3*m-=6.022xx10^20*m`

`-=6.022xx10^17*km`

And just to put some numbers in for comparison, the distance between the Earth and its moon is `384,403*km`. One light year is `9.46xx10^12*m`...and so in terms of light years....we gots...

`(6.022xx10^20*m)/(9.46xx10^12*m*"light year"^-1)-=6.4xx10^7*"light years"`...we are actually talking of intergalactic distances....and as to the mass of pennies we use to make the stack....well, we probably speak of solar masses or black holes...