The earth revolves about the sun in an elliptical orbit with mean radius

The earth revolves about the sun in an elliptical orbit with mean radius  9.3 × 10⁷ in a period of 1 year. Assuming that there are no outside influences

(a)      The earth’s kinetic energy remains constant

(b)  The earth’s angular momentum remains constant

(c)   The earth’s potential energy remains constant

(d)  All are correct

Answer: b

(21)