Just like a balloon of Helium lifts about 1.02g for being less dense than the air. Does the same principle applies to vacuum being less dense than air? And if so, how much can a ballon (1L) of vacuum lift? Ignoring the condition that to have a pressure resistant balloon would make it heavier than...

Let's say we are throwing an object from the surface of the earth, this object reaches 70,000km with initial velocity of $10713 \mathrm{m}/\mathrm{s}$ until it reaches the peak high , the g value at 70,000km is $0.068 \mathrm{m}/\mathrm{s}^2$. Now my question is: How to calculate the falling time...

Let's only assume the case of electromagnetism. If one varies the Yang-Mills-Functional one gets the Yang-Mills-equation $*d*F=0$. The whole theory can be geometrically described on principal bundles. On the associated bundle, the Klein-Gordon- or Dirac-equation also has a natural geometrical int...

Is it possible that acceleration may vary linearly with velocity. Is it practically possible, if so is there a practical example of it? By integration I was able to verify that for the above case to hold true, we need velocity to depend linearly on position, but the question remains there that is...