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JEE Main 2021 (26 Aug, Shift 1) · Applications of Dimensional Analysis

Applications of Dimensional Analysis question from JEE Main 2021 (26 Aug, Shift 1)

Q45JEE Main 2021 · 26 AUG · SHIFT 1Medium

Applications of Dimensional Analysis

If E, L, M and G denote the quantities as energy, angular momentum, mass and constant of gravitation respectively, then the dimensions of P in the formula P = EL2M−5G−-5\mathrm{G}-2 are:

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Answer: (d)

  1. [E]=ML2T−2[E] = ML^2T^{-2}, [L2]=M2L4T−2[L^2] = M^2L^4T^{-2}, [M−5]=M−5[M^{-5}] = M^{-5}, [G−2]=M2L−6T4[G^{-2}] = M^{2}L^{-6}T^{4}.
  2. Powers of M: 1+2−5+2=01 + 2 - 5 + 2 = 0; L: 2+4−6=02 + 4 - 6 = 0; T: −2−2+4=0-2 - 2 + 4 = 0.
  3. So PP is dimensionless: the answer is (d) [M0L0T0][M^0L^0T^0].
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