Post History
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, th...
Answer
#2: Post edited
by
celtschk
·
2021-08-14T14:03:47Z (over 3 years ago)
Fixed a typo
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 math 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 mass 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.
#1: Initial revision
by
celtschk
·
2021-08-14T14:02:40Z (over 3 years ago)
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 $60\\,\rm kg$ person accelerates by, say, $1\\,\rm m/s^2$, then Earth, which has a math of about $6\cdot 10^{24}\\,\rm kg$, will only accelerate with $10^{-23}\\,\rm m/s^2$, 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.