Classical Mechanics Challenge #2

[Martin]

A certain star has two planets and the "year" of one of them is 3.4 times the other's.

 

One question could be how much farther away is one than the other but

to complicate matters I wont ask that directly, but will talk about "equilibrium temperature"

 

on the nearer planet the equilibrium temperature is just right to boil water at what we think of as normal atmospheric pressure.

 

equil. temp. is how hot a dark surface facing direct sunlight will get

(one thinks of it as back-insulated so it has to get hot enough to radiate away same amount of energy as incoming)

 

have to go.

 

my question is what is equil. temp. at the farther planet?

[Martin]

this wasnt good enough.

Can someone else offer a more interesting Classical Challenge #2 problem?

Please make it fun but not too hard!

 

with this one I was looking for the fact that the equilibrium temp goes as the cube root of the orbit period

 

so if some planet's period is 8 earth years then the equilib temp at that distance from sun is HALF what it is at earth

 

if some planet's period is 27 years then equil. temp is a THIRD of what it is at our distance from sun

 

cube root of 3.4 is about 3/2

so the temperature I was looking for was 2/3 of 373 Kelvin

 

 

we have plenty of experts here could supply interesting (not too hard) problems-----Janus, Tom, SwansonT, Severian.

Please some of you post one. Call it #2, this one doesnt count.

[bloodhound]

sorry martin, but with study in maths, i am currently very out of touch with physics. but ill recommend this post to a mate who does physics.. i am sure he would be interested