Question

A planet is orbiting the sun in an elliptical orbit. Let $U$ denote the potential energy and $K$ denote the kinetic energy of the planet at an arbitrary point on the orbit and $T$ represents total energy. Choose the correct statement.

• A. $K>|U|$ at all points.
• B. $K$ is same for all points.
• C. $T$ is higher at near points and lower at far points.
• D. $K+U$ must be negative at all points.

Answer 1

The correct option is D $K+U$ must be negative at all points.

$|U|$ is always greater than $K$. Or $K+U$ must be negative at all points $K+U<0$.
For bound motion, $T$ must be negative.