Verified Solution • 2025–26 Session
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QNEET-2023-Ph-254: NEET 2023 Physics - Class 11 NEET-2023-Ph-254 Solution: The ratio of radius of gyration of a solid sphere of mass M and …
The ratio of radius of gyration of a solid sphere of mass M and radius R about its own axis to the radius of gyration of the thin hollow sphere of same mass and radius about its axis is :- 5:3 2:5
Multiple Choice Options
- A 5 : 3
- B 2 : 5
- C 5 _ : 3 _
- D 3 _ : 5 _
Step-by-Step Verified Solution
To solve this problem, we need to find the ratio of the radius of gyration for a solid sphere (K_) to the radius of gyration for a thin hollow sphere (K_) of the same mass M and radius R.
The moment of inertia (I) of a solid sphere about its own axis is given by :
I s o l i d = 2 5 M R 2
The radius of gyration (K) is related to the moment of inertia (I) and mass (M) by the formula :
I = M K 2
So for the solid sphere, we can find K_ using :
K 1 2 = I s o l i d M = 2 5 R 2
K 1 = R 2 5
Now, for a thin hollow sphere, the moment of inertia about its axis is given by :
I h o l l o w = 2 3 M R 2
We can find K_ using :
K 2 2 = I h o l l o w M = 2 3 R 2
K 2 = R 2 3
Now, we need to find the ratio K_ : K_ :
K 1 K 2 = R 2 5 R 2 3
The R terms cancel out, and we are left with :
K 1 K 2 = 2 5 2 3
Simplify by taking the square root of the fraction :
K 1 K 2 = 2 3 5 2
Now, the square root of 2 terms cancel out, giving us :
K 1 K 2 = 3 5