A planet moving along an elliptical orbit is closest to the sun at a distance $r_1$ and farthest away at a…

A planet moving along an elliptical orbit is closest to the sun at a distance $r_1$ and farthest away at a distance of $r_2$. If $y_1$ and $y_2$ are the linear velocities at these points respectively, then the ratio $\frac{y_1}{y_2}$ is
  1. $r_2 / r_1$
  2. $\left(r_2 / r_1\right)^2$
  3. $r_1 / r_2$
  4. $\left(r_1 / r_2\right)^2$

Solution

From the law of conservation of angular momentum $\begin{gathered} m r_1 y_1=m r_2 y_2 \\ r_1 y_1=r_2 y_2 \\ \frac{y_1}{y_2}=\frac{r_2}{r_1} \end{gathered}$ ~

Asked in: NEET 2011 (Screening)

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