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⚛️ Physics  ·  Units and Measurements  ·  NEET & JEE

The escape velocity from a planet is assumed to depend only on surface gravity g and radius R. Dimensional analysis gives escape velocity proportional to:

Answer: (gR).

  • A √(g/R)
  • B gR
  • C √(gR)
  • D g√R

Correct answer: C. √(gR)

Explanation: Setting [L T<sup>-1</sup>] = [L T<sup>-2</sup>]<sup>a</sup>[L]<sup>b</sup> gives a = 1/2, b = 1/2, so v is proportional to &radic;(gR).

The 7 SI Base UnitsLengthmetre (m)fundamentalMasskilogram (kg)Timesecond (s)Electric Currentampere (A)Temperaturekelvin (K)Amount ofSubstancemole (mol)LuminousIntensitycandela (cd)Every other physical quantity is derived by combining powers of these 7 base units

The 7 SI base units. All derived units (newton, joule, watt, volt, etc.) can be expressed as combinations of these 7 fundamental units raised to various powers.

Concept context

SI base units, dimensional analysis, significant figures, and error propagation. The toolkit every physics calculation relies on.

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