# A very long (length $\mathrm{L}$ ) cylindrical galaxy is made of uniformly distributed mass and has radius $R(R<<L)$. A star outside the galaxy is orbiting the galaxy in a plane perpendicular to the galaxy and passing through its centre. If the time period of star is $\mathrm{T}$ and its distance from the galaxy’s axis is $r$, then :

Question:

A very long (length $\mathrm{L}$ ) cylindrical galaxy is made of uniformly distributed mass and has radius $R(R<<L)$. A star outside the galaxy is orbiting the galaxy in a plane perpendicular to the galaxy and passing through its centre. If the time period of star is $\mathrm{T}$ and its distance from the galaxy’s axis is $r$, then :

1. $\mathrm{T} \propto \mathrm{r}$

2. $\mathrm{T} \propto \sqrt{\mathrm{r}}$

3. $\mathrm{T} \propto \mathrm{r}^{2}$

4. $\mathrm{T}^{2} \propto \mathrm{r}^{3}$

JEE Main Previous Year Single Correct Question of JEE Main from Physics Gravitation chapter.

JEE Main Previous Year April 10, 2015

Correct Option: 1

Solution:

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