Question

A planet moves around the sun. At a gıven point $P$, it is closest from the sun at a distance $d_{1}$ and has a speed $v_{1} .$ At another point $Q$, when it is farthest from the sun at a distance $d_{2}$, its speed will be

• A. $\frac{d_{1}^{2} v_{1}}{d_{2}^{2}}$
• B. $\frac{d_{2} v_{1}}{d_{1}}$
• C. $\frac{d_{1} v_{1}}{d_{2}}$
• D. $\frac{d_{2}^{2} v_{1}}{d_{1}^{2}}$

Answer 1

Answer: (C)

Angular momentum remains constant
$m v_{1} d_{1}=m v_{2} d_{2}$
$ \Rightarrow v_{2}=\frac{v_{1} d_{1}}{d_{2}}$