A cubical block is floating in a liquid with half of its volume immersed in the liquid. When the whole system accelerates upwards with acceleration of g/3, the fraction of volume immersed in the liquid will be

Let x be the fraction of volume immersed when vessel is not accelerating, thenW=UpthrustVρbg=xVρlg         x=ρbρlWhen the vessel is accelerating upward let y be the fraction of volume immersed, then Net force = Upthrust – weight Vρbg3=yVρlg+g3−Vρbg         y=ρbρlFrom the above we can see , i.e., the fraction of volume immersed does not change by the acceleration of vessel.