Nebula

09-07-1999, 06:19 AM

I was reading the old mailbag Arceive and came across the typical question of feather and hammer. If they are dropped togather which will hit the earth before?

http://www.straightdope.com/mailbag/mgravity.html

SDSTAFF member Ian promised to set someone straight but now I would like to set him straight 8-)

He gave this function which gives the force on the hammer and the feather.

F = G m1 m2

-------

r^2

Which is quite correct.

He then canceled out all the factors and found the quite correct fact that the acceleration of the hammer and the feather are exacly the same. To do this he used this equation. a = F/m

Now for the correction. Ian forgot that the equation also tells us the force that acts upon the earth do the the feather or the hammer. The force that acts on the earth form the Hammer is surly larger than the force from the feather so the earth will accelerate faster toward the hammer than the feather and there for the hammer should hit first.

Don't try to tell me that because the feather and the hammer are droppet togather that the earth accelertion should be canceled out since the feather and the hammer are not at the same place and therefor the earth accelertion matters.

By the way. The earth acceleration is small, tiny, smaller then tiny, but it is there!!!

------------------

Gunnar Valur Gunnarsson

http://www.straightdope.com/mailbag/mgravity.html

SDSTAFF member Ian promised to set someone straight but now I would like to set him straight 8-)

He gave this function which gives the force on the hammer and the feather.

F = G m1 m2

-------

r^2

Which is quite correct.

He then canceled out all the factors and found the quite correct fact that the acceleration of the hammer and the feather are exacly the same. To do this he used this equation. a = F/m

Now for the correction. Ian forgot that the equation also tells us the force that acts upon the earth do the the feather or the hammer. The force that acts on the earth form the Hammer is surly larger than the force from the feather so the earth will accelerate faster toward the hammer than the feather and there for the hammer should hit first.

Don't try to tell me that because the feather and the hammer are droppet togather that the earth accelertion should be canceled out since the feather and the hammer are not at the same place and therefor the earth accelertion matters.

By the way. The earth acceleration is small, tiny, smaller then tiny, but it is there!!!

------------------

Gunnar Valur Gunnarsson