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JEE Advanced 2020Paper 2
Exam
JEE Advanced
Year
2020
Paper
Paper 2
Subject
Physics
Chapter
Thermodynamics

JEE Advanced 2020 · Paper 2 · Physics · Thermodynamics

A spherical bubble inside water has radius R . Take the pressure...

A spherical bubble inside water has radius RR. Take the pressure inside the bubble and the water pressure to be p0.{p}_{0} . The bubble now gets compressed radially in an adiabatic manner so that its radius becomes (R−a)( R - a ). For a≪Ra ≪ R the magnitude of the work done in the process is given by (4πP0Ra2)X,\left(4\pi{P}_{0}R{a}^{2}\right)X, where XX is a constant and γ=Cp/CV=41/30\gamma = {C}_{p} / {C}_{V} = 41 / 30. The value of XX is______

Correct answer

0

Step-by-step solution

W=(ΔP)avg ×4πR2a=∣dP2⋅4πR2a∣\begin{aligned} &\mathrm{W}=(\Delta \mathrm{P})_{\text{avg }} \times 4 \pi \mathrm{R}^2 \mathrm{a} \\ &=\left|\frac{\mathrm{dP}}{2} \cdot 4 \pi \mathrm{R}^2 \mathrm{a}\right| \end{aligned}) (for small change ((\Delta \mathrm{P})_{\text{avg }}<\mathrm{P}>) arithmetic mean) (=\mathrm{PV} \text{ gamma }=\mathrm{c} \Rightarrow \mathrm{dP}=-\gamma \frac{\mathrm{P}}{\mathrm{V}} \mathrm{dV}=-\frac{\gamma \mathrm{P}_0}{\mathrm{ V}} 4 \pi \mathrm{R}^2 \mathrm{a}) (=\frac{\gamma \mathrm{P}_0}{2 \mathrm{ V}} \times 4 \pi \mathrm{R}^2 \mathrm{a} \times 4 \pi \mathrm{R}^2 \mathrm{a}) (=\frac{\gamma \mathrm{P}_0}{2 \times 4 \pi \mathrm{R}^3} 4 \pi \mathrm{R}^2 \mathrm{a} \times 4 \pi \mathrm{R}^2 \mathrm{a}) (=\left(4 \mathrm{pRP} \times \mathrm{a}^2\right) \frac{3 \gamma}{2}) (\therefore \mathrm{x}=2.05)$
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