Question Details

Statement-I : Linear momentum and moment of force have same dimensions.

Statement-II : Planck’s constant and angular momentum have same dimension.

In the light of the above statements, choose the correct answer from the options given below :

Options

A

Statement-I is correct while statement-II is false

B

Statement-I is false while statement-II is correct

C

Both statements are correct

D

Both statements are false

Correct Answer :

Statement-I is false while statement-II is correct

Solution :

The correct option/answer is: Statement-I is false while statement-II is correct.

Let's analyze both statements step-by-step using dimensional analysis.

Step 1: Analyze Statement-I
Statement-I states that linear momentum and moment of force have the same dimensions.

The formula for linear momentum (p) is:
p=mv
where m is mass and v is velocity.
The dimensions of mass are [M] and the dimensions of velocity are [LT-1].
Therefore, the dimensional formula of linear momentum is:
[p]=[MLT-1]

The moment of force (torque, τ) is given by:
τ=r×F
where r is distance and F is force.
The dimensions of distance are [L] and the dimensions of force are [MLT-2].
Therefore, the dimensional formula of moment of force is:
[τ]=[L][MLT-2]=[ML2T-2]

Comparing the two dimensional formulas:
[MLT-1][ML2T-2]
Thus, Statement-I is false.

Step 2: Analyze Statement-II
Statement-II states that Planck’s constant and angular momentum have the same dimensions.

According to Planck's equation, the energy (E) of a photon is given by:
E=hν
where h is Planck's constant and ν is frequency.
So, h=Eν.
The dimensions of energy are [ML2T-2] and the dimensions of frequency are [T-1].
Therefore, the dimensional formula of Planck's constant is:
[h]=[ML2T-2][T-1]=[ML2T-1]

The formula for angular momentum (L) is:
L=mvr
where m is mass, v is velocity, and r is radius.
Therefore, the dimensional formula of angular momentum is:
[L]=[M][LT-1][L]=[ML2T-1]

Comparing the two dimensional formulas:
[h]=[L]=[ML2T-1]
Thus, Statement-II is correct.

Conclusion:
Statement-I is false while statement-II is correct.

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