# Post History

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**#2: Post edited**

~~If you are accelerating while running on Earth, actually you are also accelerating Earth in the opposite direction. However for a given force, the acceleration is inversely proportional to mass, therefore when some $60\\, m kg$ person accelerates by, say, $1\\, m m/s^2$, then Earth, which has a ma~~**th**of about $6\cdot 10^{24}\\, m kg$, will only accelerate with $10^{-23}\\, m m/s^2$, far to low to actually notice (if accelerating for a second, the change of speed of the Earth will be so that in about three years it moved by the diameter of a proton — provided you kept running at the final speed in the same direction for the whole three years).- Basically, we can ignore the effect our motion has on the motion of the Earth because the Earth has such a large mass. But in the end, those effects are there. And yes, that means everyone of us is moving Earth around a little bit all the time. It's just that this movement is too small to actually matter.

- If you are accelerating while running on Earth, actually you are also accelerating Earth in the opposite direction. However for a given force, the acceleration is inversely proportional to mass, therefore when some $60\\,
m kg$ person accelerates by, say, $1\\,
m m/s^2$, then Earth, which has a ma
**ss**of about $6\cdot 10^{24}\\, m kg$, will only accelerate with $10^{-23}\\, m m/s^2$, far to low to actually notice (if accelerating for a second, the change of speed of the Earth will be so that in about three years it moved by the diameter of a proton — provided you kept running at the final speed in the same direction for the whole three years). - Basically, we can ignore the effect our motion has on the motion of the Earth because the Earth has such a large mass. But in the end, those effects are there. And yes, that means everyone of us is moving Earth around a little bit all the time. It's just that this movement is too small to actually matter.