Question 381
CBSE Class 11 Physics · Gravitation · Kepler's laws and satellites
For a comet in a highly elliptical orbit, identify which of linear speed, angular speed, angular momentum, kinetic energy, potential energy and total energy remain constant.
Solution to Question 381
Complete workingGravity is a central conservative force. Hence its torque about the Sun is zero and mechanical energy is conserved, while r and speed vary.
\[\begin{aligned}\vec\tau &= \vec r\times\vec F\\&= 0\Rightarrow\vec L\\&= \text{constant}\end{aligned}\]
\[K+U=\text{constant}\]
Final answer
\[\text{Only angular momentum and total mechanical energy remain constant}\]