Understanding Entropy and Free Falling Objects in a Vacuum System

[kimpantip]

Dear sir,

Hi, Everyone. I have a question about entropy. If the object falls without air resistant (vacuum system) , Is entropy changed? If ΔS=0, it means reversible, is it possible that the object can go back to the original height? I know that it is impossible but can we explain that ΔS >0.
Within the condition as following:
*** Focus on within the space (free falling under gravity)

Thank you very much

 

[mfb]

If the object falls without air resistant (vacuum system) , Is entropy changed? If ΔS=0, it means reversible, is it possible that the object can go back to the original height?

What do you think?

I know that it is impossible

Why? Assuming there are no other mechanisms where energy gets lost (inelastic collisions for example).

 

[kimpantip]

What do you think?

Why? Assuming there are no other mechanisms where energy gets lost (inelastic collisions for example).

The thing that I wonder is how can entropy increase while the object is falling in spite of no air resistant and no collision on the ground.

 

[mfb]

That's my question: why do you think it would increase?

 

[kimpantip]

why do you think it would increase?

ifΔs=0 it reversible, object is able to rise! so i think that Δs>0

 

[mfb]

ifΔs=0 it reversible, object is able to rise!

Sure it is, and it will do so after a perfect elastic collision (or a frictionless U-shaped ramp).