Quantrex Academy · Free JEE Advanced PYQ solutions
JEE Advanced Physics Thermodynamics 2020 JEE Advanced 2020 (Paper 2)

JEE Advanced Physics Question (2020) — Solution

Question

A spherical bubble inside water has radius  R . Take the pressure inside the bubble and the water pressure to be  p 0 . The bubble now gets compressed radially in an adiabatic manner so that its radius becomes  ( R - a ) . For  a ≪ R the magnitude of the work done in the process is given by 4 π P 0 R a 2 X , where  X is a constant and  γ = C p / C V = 41 / 30 . The value of  X is______

Options

  1. A. A
  2. B. B
  3. C. C
  4. D. D

Answer

A. A

Step-by-step solution

\( aligned & W =( P )_ avg 4 R ^2 a \\ &= | dP 2 4 R ^2 a | aligned \) (for small change \(( P )_ avg \) arithmetic mean) \(= PV gamma = c dP =- P V dV =- P _0 ~V 4 R ^2 a \) \(= P _0 2 ~V 4 R ^2 a 4 R ^2 a \) \(= P _0 2 4 R ^3 4 R ^2 a 4 R ^2 a \) \(= (4 pRP a ^2 ) 3 2 \) \( x =2.05\)

Practice more on Quantrex App →

Related: Physics — Thermodynamics · All PYQ Banks