A rocket is fired vertically from the earth with an acceleration of 2g, where g is the gravitational acceleration. On an inclined plane inside the rocket, making an angle $\mathrm{\theta }$ with the horizontal, a point object of mass m is kept. The minimum coefficient of friction ${\mathrm{\mu }}_{\mathrm{m}\mathrm{i}\mathrm{n}}$ between the mass and the inclined surface such that the mass does not move is:

• A

  $\tan 2\mathrm{\theta }$
• Correct answer
  B

  $\tan \mathrm{\theta }$
• C

  $3\tan \mathrm{\theta }$
• D

  $2\tan \mathrm{\theta }$

Solution

$3\mathrm{m}\mathrm{g}\sin \mathrm{\theta }=\mathrm{\mu }3\mathrm{m}\mathrm{g}\cos \mathrm{\theta }$

$\mathrm{\mu }=\tan \mathrm{\theta }$

Hence, the correct answer is option: 'B'.