A planet is revolving round the sun in an elliptical orbit as shown in figure. Select correct alternative(s)

Options

A. a) Its total energy is negative at D.
B. b) It s angular momentum is constant
C. c) Net torque on the planet about sun is zero
D. d) Linear momentum of the planet is conserved

Answer

A, B, C

Explanation

For (A) : For a bond system, the total energy is always negative.
For (B) : For central force field, angular momentum is always conserved.
For (C) : For central force field, torque `=0`
For (D) : In presence of external force, linear momentum is not conserved.