Question

As shown in figure, $a$ planet revolves in elliptical orbit around the sun, where $K.E.$ of the planet is maximum :

• A. at $P_{4}$
• B. at $P_{1}$
• C. at $P_{2}$
• D. at $P_{3}$

Answer 1

Answer: (A)

at $P_{4}$

Answer 2

Since angular momentum is conserved Therefore, $I_{1} \omega_{1}=I_{2} \omega_{2}$ or $M R_{1}^{2} \omega_{1}=M R_{2}^{2} \omega_{2}$ or $M R_{1} v_{1}=M R_{2} v_{2}$ At $P_{4}$ the value of $R$ is minimum Hence the velocity is maximum or kinetic energy will be maximum.