Question

In Planetary motion

• A. The angular speed remains constant
• B. The total angular momentum remains constant
• C. The linear speed remains constant
• D. Neither the angular momentum nor angular speed remains constant

Answer 1

Answer: (B)

The total angular momentum remains constant

In planetary motion, there is no external torque. Hence from the equation
$\frac{\overrightarrow{dL}}{dt}={\overrightarrow{\tau }}_{ext}.,{\overrightarrow{\tau }}_{ext}=0\Rightarrow L=$ constant