KCET · Physics · Rotational Motion
The angular momentum of a moving body remains constant, if
- A net external force is applied
- B net pressure is applied
- C net external torque is applied
- D net external torque is not applied
Answer & Solution
Correct Answer
(D) net external torque is not applied
Step-by-step Solution
Detailed explanation
According to Newton's second law for rotational motion, the rate of change of angular momentum of a body is equal to the net external torque acting on it.
\(\dfrac{d\vec{L}}{dt} = \vec{\tau}_{ext}\)
If the net external torque applied on the body is zero (\(\vec{\tau}_{ext} = 0\)), then \(\dfrac{d\vec{L}}{dt} = 0\).
This implies that \(\vec{L} = \text{constant}\).
Thus, the angular momentum of a moving body remains constant if net external torque is not applied.
Answer: net external torque is not applied
\(\dfrac{d\vec{L}}{dt} = \vec{\tau}_{ext}\)
If the net external torque applied on the body is zero (\(\vec{\tau}_{ext} = 0\)), then \(\dfrac{d\vec{L}}{dt} = 0\).
This implies that \(\vec{L} = \text{constant}\).
Thus, the angular momentum of a moving body remains constant if net external torque is not applied.
Answer: net external torque is not applied
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