Ask Questions, Get Answers

Want to ask us a question? Click here
Browse Questions
Home  >>  JEEMAIN and AIPMT  >>  Physics  >>  Class11  >>  Gravitation
0 votes

A light planet revolving around a very massive star in a circular orbit of radius R with a period of revolution T. If the gravitational force of attraction between the planet and star is proportional to $R^{\large\frac{-5}{2}}$ then $T^2$ is proportional to

\[(a)\;R^3 \quad (b)\;R^{\frac{7}{2}} \quad (c)\;R^{\frac{3}{2}} \quad (d)\;R^{\frac{9}{2}}\]

Can you answer this question?

1 Answer

0 votes
Gravitational force $ \alpha\;R ^{\large\frac{-5}{2}}$
Centripelal force $\alpha\; R^{\large\frac{-5}{2}}$
$m R w^2 \;\alpha\; R^{\large\frac{-5}{2}}$
$w^2 \;\alpha \; R^{\large\frac{-5}{2} -1}$
$w^2 \;\alpha \; R^{\large\frac{-7}{2}}$
$\large\bigg(\frac{2 \pi}{T}\bigg)^2 \alpha\; $$R^{\large\frac{-7}{2}}$
$T^2 \alpha\; R^{\large\frac{7}{2}}$
Hence b is the correct answer.


answered Aug 21, 2013 by meena.p
edited Feb 17, 2014 by meena.p

Related questions

Ask Question
student study plans
JEE MAIN, CBSE, NEET Mobile and Tablet App
The ultimate mobile app to help you crack your examinations
Get the Android App