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A balloon is made of a material of surface tension S and its inflation outlet (from where gas is filled in it) has small area A. It is filled with a…

NEET UG 2025 — Physics Mechanics

2025mcqhard

A balloon is made of a material of surface tension SSS and its inflation outlet (from where gas is filled in it) has small area AAA. It is filled with a gas of density ρ\rhoρ and takes a spherical shape of radius RRR. When the gas is allowed to flow freely out of it, its radius changes from RRR to 0 (zero) in time TTT. If the speed η(r)\eta(r)η(r) of gas coming out of the balloon depends on rrr as rαr^\alpharα and T∝SαAβργRδT \propto S^\alpha A^\beta \rho^\gamma R^\deltaT∝SαAβργRδ then

Official previous-year question

Held on 30 Apr 2025 · Verified 9 Jul 2026.

Options

  1. A

    a=12,α=12,β=−1,γ=+1,δ=32a=\frac{1}{2}, \alpha=\frac{1}{2}, \beta=-1, \gamma=+1, \delta=\frac{3}{2}a=21​,α=21​,β=−1,γ=+1,δ=23​

  2. B

    a=−12,α=−12,β=−1,γ=−12,δ=52a=-\frac{1}{2}, \alpha=-\frac{1}{2}, \beta=-1, \gamma=-\frac{1}{2}, \delta=\frac{5}{2}a=−21​,α=−21​,β=−1,γ=−21​,δ=25​

  3. C

    a=−12,α=−12,β=−1,γ=12,δ=72a=-\frac{1}{2}, \alpha=-\frac{1}{2}, \beta=-1, \gamma=\frac{1}{2}, \delta=\frac{7}{2}a=−21​,α=−21​,β=−1,γ=21​,δ=27​

  4. D

    a=12,α=12,β=−12,γ=12,δ=72a=\frac{1}{2}, \alpha=\frac{1}{2}, \beta=-\frac{1}{2}, \gamma=\frac{1}{2}, \delta=\frac{7}{2}a=21​,α=21​,β=−21​,γ=21​,δ=27​

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