Solved papers for JEE Main & Advanced JEE Main Paper (Held On 19 April 2014)

done JEE Main Paper (Held On 19 April 2014) Total Questions - 1

• question_answer1) A black coloured solid sphere of radius R and mass M is inside a cavity with vacuum inside. The walls of the cavity are maintained at temperature \[{{T}_{0}}.\] The initial temperature of the sphere is \[3{{T}_{0}}.\]If the specific heat of the material of the sphere varies as \[\alpha {{T}^{3}}\]per unit mass with the temperature T of the sphere, where \[\alpha \] is a constant, then the time taken for the sphere to cool down to temperature \[2{{T}_{0}}\]  will be (\[\sigma \]is Stefan Boltzmann constant)     JEE Main Online Paper (Held On 19 April 2016)
  A)
  \[\frac{M\alpha }{4\pi {{R}^{2}}\sigma }\ln \left( \frac{3}{2} \right)\]      
  done clear
  B)
  \[\frac{M\alpha }{4\pi {{R}^{2}}\sigma }\ln \left( \frac{16}{3} \right)\]
  done clear
  C)
  \[\frac{M\alpha }{16\pi {{R}^{2}}\sigma }\ln \left( \frac{16}{3} \right)\]  
  done clear
  D)
  \[\frac{M\alpha }{16\pi {{R}^{2}}\sigma }\ln \left( \frac{3}{2} \right)\]
  done clear
  View Answer play_arrow