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Angular momentum is conserved...

Angular momentum is conserved

A

always

B

never

C

when external force is absent

D

when external torque is absent

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The correct Answer is:
To solve the question regarding the conservation of angular momentum, we will analyze each option based on the principles of physics. ### Step-by-Step Solution: 1. **Understanding Angular Momentum**: Angular momentum (\(L\)) of a system is defined as the product of the moment of inertia (\(I\)) and the angular velocity (\(\omega\)). Mathematically, it can be expressed as: \[ L = I \cdot \omega \] 2. **Law of Conservation of Angular Momentum**: The law states that if no external torque acts on a system, the total angular momentum of that system remains constant. This means that angular momentum is conserved in the absence of external influences. 3. **Analyzing the Options**: - **Option A**: Always conserved. - This is incorrect because angular momentum is not conserved in the presence of external torques. - **Option B**: Never conserved. - This is also incorrect as there are conditions (specifically, when no external torque is present) under which angular momentum is conserved. - **Option C**: When external force is absent. - This is misleading because angular momentum can still change due to external forces if those forces create a torque. Therefore, this option is not entirely accurate. - **Option D**: When external torque is absent. - This is correct. According to the conservation law, angular momentum is conserved when there is no external torque acting on the system. 4. **Conclusion**: Based on the analysis, the correct answer is **Option D**, which states that angular momentum is conserved when external torque is absent. ### Final Answer: **Option D: When external torque is absent.** ---
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