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## #1 2018-02-03 02:18:39

Hannibal lecter
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Registered: 2016-02-11
Posts: 225
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### important question about Volum of sphare

Hi,

write formula representing the function which it the volume of a sphere is proportional to the cube of its radius, r. ?

I found the answer if V= kr^3 which is V = 3/4*pi*r^3

how is that be??

before I look to the answer I solve it in my papers and wrote ( V= r^3 )

but I didn't wrote the 3/4*pi*!!
from where the solver bring this values ...

Wisdom is a tree which grows in the heart and fruits on the tongue

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## #2 2018-02-03 02:27:30

Hannibal lecter
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Registered: 2016-02-11
Posts: 225
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### Re: important question about Volum of sphare

The average velocity, v, for a trip over a ﬁxed distance, d, is inversely proportional to the time of travel, t.

which is v= d/t

there is no a constant of proportionality here why?

with compare to other questions like that ( The number of animal species, N, of a certain body length, l, is inversely proportional to the square of l. )
which it N =k/l^2

now there is a constant again!

I got confused, when we put that " k " and when not?

Wisdom is a tree which grows in the heart and fruits on the tongue

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## #3 2018-02-03 03:53:32

zetafunc
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Registered: 2014-05-21
Posts: 2,200
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### Re: important question about Volum of sphare

Hannibal lecter wrote:

The average velocity, v, for a trip over a ﬁxed distance, d, is inversely proportional to the time of travel, t.

which is v= d/t

there is no a constant of proportionality here why?

There is: it's
, the fixed distance. Since the distance doesn't change, that's the 'constant of proportionality'.

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