Weightlessness. (1 Viewer)

[CHUDYMASTER]

What are the different ways of explaining weightlessness experienced on an elevator?

I have a vague idea from last year, but I forget and I'm sure there's more than one explanation.

 

[McLake]

1) "g" down balances "a" up so no resultant force, so no weight.

2) To feel weight a normal force must be acting on you. If "a" = "g" there is no normal force, so no weight ...

 

[CHUDYMASTER]

Correct
Although aren't your first and second points the same?

 

[McLake]

Originally posted by CHUDYMASTER
Correct
Although aren't your first and second points the same?

Well, I'm not sure what you mean by "two ways of explaining it"

 

[CHUDYMASTER]

Never mind, one shall doo doo.

 

[marsesbars]

Originally posted by McLake
1) "g" down balances "a" up so no resultant force, so no weight.

I think (?) weightless is where there is no reaction force to balance our weight.

If our weight (the "g" down) is balanced, we don't feel weightless. Think about it: standing on the earth, we feel a "g" down, and the ground gives an "a" up to balance it - no resultant force, but we don't feel weightless.

I think you said what I said in the second point:

Originally posted by McLake

2) To feel weight a normal force must be acting on you. If "a" = "g" there is no normal force, so no weight ...

By the way, "weightlessness" is a misleading name. We can have weight provided by the Earth and still feel "weightless" (like what happens with astronauts in a satellite), but that's 'coz there's no reaction force to our weight. "Weightlessness" should be called "NoReactionForceNess"