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JEE Main 2011 (AIEEE) · Surface Energy & Work Done

Surface Energy & Work Done question from JEE Main 2011 (AIEEE)

Q30JEE Main 2011 · AIEEEMedium

Surface Energy & Work Done

Work done in increasing the size of a soap bubble from a radius of 3 cm3\text{ cm} to 5 cm5\text{ cm} is nearly (Surface tension of soap =0.03 N m−1,= 0.03\text{ N m}^{-1},

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Answer: (c)

  1. W=8πT(r22−r12)W = 8\pi T (r_2^2 - r_1^2)
  2. W=8π×0.03×(25−9)×10−4=3.84π×10−4 JW = 8\pi \times 0.03 \times (25 - 9)\times10^{-4} = 3.84\pi\times10^{-4}\text{ J}
  3. W=0.384π mJ≈0.4π mJW = 0.384\pi\text{ mJ} \approx 0.4\pi\text{ mJ}
  4. So the answer is (c) 0.4π mJ0.4\pi\text{ mJ}.
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