Practice portal › Gravitation › Energy of a Satellite and Orbit Changes
Asked in JEE Main 6th April 2nd Shift 2023 · Weightlessness and mixed concepts
Planetary orbits are ellipses, not circles, so the sun-planet distance changes through the year.
Angular momentum L=mvr sin θ is conserved, which forces the planet to speed up near perihelion and slow down near aphelion. This is Kepler's second law.
So the linear speed of a planet is not constant, and statement 1 is the incorrect one.
The other three all hold: circular orbits have fixed speed, the earth's recoil displacement is negligible because of its huge mass, and the total energy of an elliptical orbit is conserved.
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