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⚛️ Physics  ·  Units and Measurements  ·  NEET & JEE

A new system of units is defined where the unit of mass is 2 kg, the unit of length is 2 m, and the unit of time is 2 s. What is the value of 16 J of energy in this new system?

Answer: 8 new units.

  • A 16 new units
  • B 32 new units
  • C 8 new units
  • D 4 new units

Correct answer: C. 8 new units

Explanation: Energy has dimensions [ML²T⁻²], so n<sub>2</sub> = n<sub>1</sub> × (M1/M2)(L<sub>1</sub>/L<sub>2</sub>)²(T<sub>1</sub>/T<sub>2</sub>)⁻² = 16 × (1/2) × (1/2)² × (2/1)² = 16 × 0.5 × 0.25 × 4 = 8 new units.

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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