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Qmechanic ♦
Qmechanic ♦
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Given Newton's Third law, why don't we have to include acceleration or energy lost to earthEarth in calculations?

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edit approved Aug 20, 2020 at 18:34
Urb
edit approved Aug 20, 2020 at 18:34
Urb
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Given NewtonsNewton's Third law, why dontdon't we have to include acceleration or Energyenergy lost to earth in calculations?

This is probably an elementary question, but I am trying to help my nephew answer a worry. His question is: given newtonsNewton's third law, when a ball is thrown up in the air, we would push the earth a little downward. But whatever acceleration imparted and distance traveled during the throw the earth moved, why don't we have to take this into consideration?

I know from experience it is because we assume the earth didn't move. But iI want to give him a better reason. I think the following, can someone confirm it is right we can assume it doesn't move because:

  1. There are thousands of things happening at once, therefore all these actions/reactions tend to cancel out.
  2. Earth is too massive to make a difference.
  3. Our force might only compress part of earth, not earth as a whole.
  4. Even if it did move or accelerate when the ball was thrown, when they collide as it comes back to ground, technically each would stop one another.

Therefore, we can safely ignore in all practical problems. This correct? Darn it, should have kept my highschool physics book given all this remote learning.

Given Newtons Third law, why dont we have to include acceleration or Energy lost to earth in calculations?

This is probably an elementary question, but I am trying to help my nephew answer a worry. His question is given newtons third law, when a ball is thrown up in the air, we would push the earth a little downward. But whatever acceleration imparted and distance traveled during the throw the earth moved, why don't we have to take this into consideration?

I know from experience it is because we assume the earth didn't move. But i want to give him a better reason. I think the following, can someone confirm it is right we can assume it doesn't move because:

  1. There are thousands of things happening at once, therefore all these actions/reactions tend to cancel out.
  2. Earth is too massive to make a difference.
  3. Our force might only compress part of earth, not earth as a whole.
  4. Even if it did move or accelerate when the ball was thrown, when they collide as it comes back to ground, technically each would stop one another.

Therefore, we can safely ignore in all practical problems. This correct? Darn it, should have kept my highschool physics book given all this remote learning.

Given Newton's Third law, why don't we have to include acceleration or energy lost to earth in calculations?

This is probably an elementary question, but I am trying to help my nephew answer a worry. His question is: given Newton's third law, when a ball is thrown up in the air, we would push the earth a little downward. But whatever acceleration imparted and distance traveled during the throw the earth moved, why don't we have to take this into consideration?

I know from experience it is because we assume the earth didn't move. But I want to give him a better reason. I think the following, can someone confirm it is right we can assume it doesn't move because:

  1. There are thousands of things happening at once, therefore all these actions/reactions tend to cancel out.
  2. Earth is too massive to make a difference.
  3. Our force might only compress part of earth, not earth as a whole.
  4. Even if it did move or accelerate when the ball was thrown, when they collide as it comes back to ground, technically each would stop one another.

Therefore, we can safely ignore in all practical problems. This correct? Darn it, should have kept my highschool physics book given all this remote learning.

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Kevin C Speltz
Kevin C Speltz
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Given Newtons Third law, why dont we have to include acceleration or Energy lost to earth in calculations?

This is probably an elementary question, but I am trying to help my nephew answer a worry. His question is given newtons third law, when a ball is thrown up in the air, we would push the earth a little downward. But whatever acceleration imparted and distance traveled during the throw the earth moved, why don't we have to take this into consideration?

I know from experience it is because we assume the earth didn't move. But i want to give him a better reason. I think the following, can someone confirm it is right we can assume it doesn't move because:

  1. There are thousands of things happening at once, therefore all these actions/reactions tend to cancel out.
  2. Earth is too massive to make a difference.
  3. Our force might only compress part of earth, not earth as a whole.
  4. Even if it did move or accelerate when the ball was thrown, when they collide as it comes back to ground, technically each would stop one another.

Therefore, we can safely ignore in all practical problems. This correct? Darn it, should have kept my highschool physics book given all this remote learning.