Mass Air Bubble: Negative Effects in Material Medium

[Himal kharel]

Why is the mass of air bubble in material medium considered to be negative?

 

[berkeman]

Why is the mass of air bubble in material medium considered to be negative?

Please provide a link where this is used. Negative mass for a bubble would seem to be a clumsy computational tool.

 

[DaveC426913]

Why is the mass of air bubble in material medium considered to be negative?

Well, at first glance: the air bubble is going to be bouyant, so yeah, a self-contained discrete object (and no skin, like a balloon has) with, essentially, a negative mass. If the material is sensitive to strain, the bubble would push upward.

 

[RedX]

F=mg-\frac{m}{\rho_{air}}\rho_{water}g=<br /> (m(1-\frac{\rho_{water}}{\rho_{air}}))g<br />
so that the mass gets modified to:
m \rightarrow m(1-\frac{\rho_{water}}{\rho_{air}})
which can be negative?

I think what's more common is to define an effective gravity rather than an effective mass, and have:
g \rightarrow g(1-\frac{\rho_{water}}{\rho_{air}})