Some weird physics questions I'd like answering please

[Gondur]

Hello there physicists!

Here are two questions I'd like you to answer please.

If the population keeps increasing and if we keep building infrastructure, could the Earth's diameter decrease? In other words, could we crush the Earth like crushing a tin can in the palm of our hands?

Surely the net mass of the Earth is constant; it's just that we have rearranged its minerals and ores into structures like buildings for our usage and they in fact both have the same mass.

What about people? Do they add to the mass of the Earth or does a person's existence decrease another 'resource', so everything balances out?

Does density matter? Is it possible to make something more dense and increase the mass of the Earth without decreasing something else in the process?

___________________________________________________________________________

If another planet slowly got closer to the Earth such that the Earth's atmosphere was touching the planet's atmosphere, would there be a reaction of some kind? Would heat be generated even if it moved at a rate of 1 cm per minute towards the Earth?

Is is possible for the Earth's atmosphere to connect to the other planets atmosphere such that a symbiotic relationship could exist between both planets? Would both atmosphere mix together and produce a different kind of 'diluted' atmosphere shrouding both planets like adding orange juice to water?

Thanks!

 

[A.T.]

Surely the net mass of the Earth is constant;

Approximately. Meteoroids add a bit.

What about people? Do they add to the mass of the Earth or does a person's existence decrease another 'resource', so everything balances out?

You never noticed that people eat stuff?

 

[CWatters]

Hello there physicists!

Here are two questions I'd like you to answer please.

If the population keeps increasing and if we keep building infrastructure, could the Earth's diameter decrease? In other words, could we crush the Earth like crushing a tin can in the palm of our hands?

Surely the net mass of the Earth is constant; it's just that we have rearranged its minerals and ores into structures like buildings for our usage and they in fact both have the same mass.

I believe you are correct. Basically we just keep rearranging stuff.

Overall it seems the planet is loosing mass. Explanation here..

http://science-beta.slashdot.org/story/12/02/02/1844205/is-the-earth-gaining-or-losing-mass

What about people? Do they add to the mass of the Earth or does a person's existence decrease another 'resource', so everything balances out?

The above article suggests that global warming is increasing the mass of the earth. Does that count?

Does density matter? Is it possible to make something more dense and increase the mass of the Earth without decreasing something else in the process?

Taking something on Earth and making it more dense doesn't increase the mass of the earth.

I suppose that article implies if you were to split the world oceans into hydrogen and oxygen then perhaps more hydrogen would leak into space making the Earth lighter. However that would cause other problems and effects.

___________________________________________________________________________

If another planet slowly got closer to the Earth such that the Earth's atmosphere was touching the planet's atmosphere, would there be a reaction of some kind? Would heat be generated even if it moved at a rate of 1 cm per minute towards the Earth?

Two planets orbiting each other in close proximity would cause strong tidal effects. I'm not an expert on this but I imagine that alone would heat up the planets as happens on Io...

http://www.planetaryexploration.net/jupiter/io/tidal_heating.html

 

[voko]

If another planet slowly got closer to the Earth such that the Earth's atmosphere was touching the planet's atmosphere, would there be a reaction of some kind? Would heat be generated even if it moved at a rate of 1 cm per minute towards the Earth?

Depending on how one defines the limit of the atmosphere, the distance between the surfaces of the planets would be in the 100-1000 km range. That is (much) less than the radius of the Earth, and so the planets would exert a very strong gravitational force onto each other. So strong, that the planets would have to move at a very high speed with regard to each other to keep the separation - otherwise they would collide in a matter of minutes, if not seconds. Either way, this will be highly disruptive to everything on the Earth - including life, too.

 

[A.T.]

Depending on how one defines the limit of the atmosphere, the distance between the surfaces of the planets would be in the 100-1000 km range. That is (much) less than the radius of the Earth, and so the planets would exert a very strong gravitational force onto each other. So strong, that the planets would have to move at a very high speed with regard to each other to keep the separation - otherwise they would collide in a matter of minutes, if not seconds. Either way, this will be highly disruptive to everything on the Earth - including life, too.

The main problem would be the tidal forces:
http://en.wikipedia.org/wiki/Roche_limit