Kepler's second law states that the line joining a planet to the sun sweeps equal areas in equal times. This is equivalent to conservation of:
ALinear momentum
BEnergy
CKinetic energy
DAngular momentum
Answer & Solution
Correct answer: D. Angular momentum
Areal velocity = (1/2) r v sinθ = L/(2m), where L is angular momentum. Since gravity is a central force, torque about sun is zero, so L is conserved. Kepler's 2nd law is angular momentum conservation.
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