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MHT CET 2025 (20 Apr, Shift 2) · Pressure in a Fluid

Pressure in a Fluid question from MHT CET 2025 (20 Apr, Shift 2)

Q7MHT CET 2025 · 20 APR · SHIFT 2Medium

Pressure in a Fluid

The temperature of an air bubble while rising from bottom to surface of a lake remains constant but diameter is doubled. If pressure on the surface is hh meter of mercury column and relative density of mercury is ' ρ\rho ' then the depth of the lake is

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Answer: (b)

  1. Diameter doubles, so volume becomes 8 times. Boyle's law: PbottomV=Psurface(8V)P_{bottom}V = P_{surface}(8V), so Pbottom=8PsurfaceP_{bottom} = 8P_{surface}.
  2. Surface pressure hh m of mercury =hρ= h\rho m of water.
  3. hρ+d=8hρ⇒d=7hρh\rho + d = 8h\rho \Rightarrow d = 7h\rho
  4. So the answer is (b) 7hρ7h\rho.
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