Two non-mixing liquids of densities and n (n > 1) are put in a container. The height of each liquid is h. A solid cylinder of length L and density d is put in this container. The cylinder floats with its axis vertical and length pL (p < 1) in the denser liquid. The density d is equal to
- \2 + (n - 1)p\
- \1 + (n - 1)p\
- \1 + (n + 1)p\
- \2 + (n + 1)p\
Answer
(2) \1 + (n - 1)p\
Solution
The denser liquid (n ) is at the bottom; the cylinder has length pL in it and the remaining length (1 - p)L in the lighter liquid ( ).
Let A = area of cross-section. For floating, weight = total buoyant force:
ALd g = A(pL)(n )g + A(1 - p)L g
⇒ d = pn + (1 - p)
∴ d = \1 + (n - 1)p\
Answer: (2)