Question Details

The dimensions of universal qravitational constant are

Options

A

[M⁻¹L³T⁻²]

B

[ML²T⁻¹]

C

[M⁻²L³T⁻²]

D

[M⁻²L²T⁻¹]

Correct Answer :

[M⁻¹L³T⁻²]

Solution :

The correct answer is Option 1: [M⁻¹L³T⁻²].

To find the dimensions of the universal gravitational constant (G), we start with Newton's law of universal gravitation. The gravitational force (F) between two masses (m1 and m2) separated by a distance (r) is given by the formula:
F=Gm1m2r2

Rearranging this formula to solve for the gravitational constant G, we get:
G=Fr2m1m2

Now, we substitute the dimensional formulas of the individual physical quantities into this expression:

  • Force (F) has dimensions: [MLT-2]
  • Distance (r) has dimensions: [L], so r2 has dimensions: [L2]
  • Masses (m1 and m2) have dimensions: [M], so their product m1m2 has dimensions: [M2]

Substituting these dimensions into the rearranged equation:
[G]=[MLT-2][L2][M2]

Combining the terms in the numerator:
[G]=[ML3T-2][M2]

Simplifying the powers of M by bringing the denominator to the numerator, we obtain:
[G]=[M1-2L3T-2]
[G]=[M-1L3T-2]

Thus, the dimensional formula of the universal gravitational constant is [M⁻¹L³T⁻²].

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