1)A sphere of a given mass is put in a non viscous liquid. The sphere is released, and it moves down in the liquid. My doubt is, is the mechanical energy of the system decreasing?
The answer given in the book is no, but I dont have access to the reason. I could not think why, because, according to me, when an object is freely falling, only then is the mechanical energy conserved, but here it is experiencing an upward buoyant force, so I think this should mean that mechanical energy is not same. Is it increasing? If so, why?
2)a) The situation is the same as above, now the question is, is the gravitational potential energy of the liquid continuously increasing?
b) the liquid is now viscous, and the sphere is falling at terminal velocity. Now, is the gravitational potential energy of the liquid continuously increasing??
To for both 2a and 2b, the answer is yes. But again, I dont see how this is happening, as the level of liquid has already risen. now if the sphere moves down further, why should it have an impact on the gravitational potential energy of the liquid?