Question
Question: A tube with both ends open floats vertically in water. The portion out of the water is of length 10 ...
A tube with both ends open floats vertically in water. The portion out of the water is of length 10 cm. Oil with a density 800 kg/m3 is poured into the tube. If tube can be completely filled with oil, then its length is
A
50 cm
B
60 cm
C
90cm
D
100 cm
Answer
100 cm
Explanation
Solution
After oil is filled up, pressure at the level of lower end should
equate if measured from inside and outside of the tube.
Suppose depth of oil is x cm then :
1000.g. [(l - 10)cm] = 800g. (× cm) + 1000g[(l - x)cm]
⇒ x = 50 cm
Now, pressure difference due to x cm depth of oil is equal to
pressure difference due to {(l - x -10)cm of water.
⇒ 800. g.x = 1000g (l - 60)
⇒ l = 100 cm