Gravity & Mass: Impact on Earth

[Funkmaster W]

First off i will start with a question. When the mass of the Earth was found was the mass of the current population taken into account? If so then technically as the years progress and population increases the mass of Earth would increase. If the population was not taken into account shouldn't it have been since just as a generalization the current population's mass is about half of Earth's mass. Now based on that if the mass of Earth is ever increasing won't gravity also change? Based off of the equation a = (G * m)/(r^2) where a is acceleration due to gravity G is the gravitational constant 6.67x10^-11, m is the mass of Earth and r is the radius of earth. Could someone please give some insight on this.

 

[DaveC426913]

First off i will start with a question. When the mass of the Earth was found was the mass of the current population taken into account? If so then technically as the years progress and population increases the mass of Earth would increase. If the population was not taken into account shouldn't it have been since just as a generalization the current population's mass is about half of Earth's mass. Now based on that if the mass of Earth is ever increasing won't gravity also change? Based off of the equation a = (G * m)/(r^2) where a is acceleration due to gravity G is the gravitational constant 6.67x10^-11, m is the mass of Earth and r is the radius of earth. Could someone please give some insight on this.

OK, the hard (and wrong) answer:
Human bio-mass: 10^11
Earth mass: 10^24
Difference: 1 part in 10,000,000,000,000; that's a 13 decimal place fraction.
To how many decimal places is the gravitational constant known? You've shown 2 (6.67). So, 6.67 versus 6.67000000000001 I guess?

Now the easy (and right) answer (you'll kick yourself):
Um. Exactly where do you think human babies come from? Do you think they pop into existence from a white hole? Where does their mass come from?

 

[bassplayer142]

The Earth is not a closed system. There is meteorites and all manner of matter coming down to earth. Most importantly, the light from the sun has energy. E=mc^2

 

[Nick666]

We are all children of the...meteorites.

 

[D H]

The Earth is not a closed system. There is meteorites and all manner of matter coming down to earth.

So? Is the increase in mass due to this mass influx at all significant? An upper estimate on this mass influx is 78,000 tons per year, or about 1×10^-17 Earth masses per year. The uncertainty in the Earth's mass is dominated by the uncertainty in G, which is about one part in 10⁴. It would take about 10 trillion years of continued accumulation for the influx to be significant by this measure. Eliminating this uncertainty in G by expressing the Earth's mass as the product μ_⊕=G*M_⊕=398,600.4418±0.0009 km³s^–2 helps, but not much. It will still take about a billion years of accumulation to make the change in the Earth's mass significant even by this much more sensitive metric.

Most importantly, the light from the sun has energy. E=mc^2

And how is this important? (Hint: It isn't.) Think about it for just a bit.