Question Details

If E and G respectively denote energy and gravitational constant, then E/G has the dimensions of :

Options

A

[M²] [L⁻¹] [T⁰]

B

[M] [L⁻¹] [T⁻¹]

C

[M] [L⁰] [T⁰]

D

[M²] [L⁻²] [T⁻¹]

Correct Answer :

[M²] [L⁻��] [T⁰]

Solution :

The correct option is [M²] [L⁻¹] [T⁰].

To find the dimensions of the ratio of energy to the gravitational constant, we determine the individual dimensional formulas of both quantities.

1. Dimensional Formula of Energy (E):
Energy is defined as work done, which is the product of force and displacement.

E=Force×Displacement

The dimensional formula of Force is [MLT-2], and for Displacement it is [L].
Therefore, the dimensional formula of energy E is:

[E]=[MLT-2]×[L]=[ML2T-2]

2. Dimensional Formula of the Gravitational Constant (G):
According to Newton's Law of Gravitation, the force (F) between two masses m1 and m2 separated by distance r is given by:

F=Gm1m2r2

Rearranging the formula to solve for G:

G=Fr2m1m2

Substituting the dimensional formulas for Force [MLT-2], distance [L], and mass [M]:

[G]=[MLT-2]×[L2][M]×[M]=[M-1L3T-2]

3. Dimensions of the Ratio E/G:
Dividing the dimensional formula of energy by the dimensional formula of the gravitational constant:

[EG]=[ML2T-2][M-1L3T-2]

Applying the laws of exponents:

[EG]=[M1-(-1)L2-3T-2-(-2)]

[EG]=[M2L-1T0]

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