Question

CHOOSE AN OPTION GIVINF AN EXPLAINATION IN FAVOR OF UR ANSWER

Answer 1

(1)     Binding energy per nucleon = total binding energy / mass number
         hence 
          total binding energy of helium  = 7*4 = 28 MeV.
          total binding energy of deutron = 1.1*2 = 2.2 MeV 
          deutron + deutron  ---------------------------> He + Q
  where Q = energy = total energy of product - total energy of reactant 
hence energy released = 28 - 2*2.2 = 23.6 MeV.
hence option (c) is correct. 
(2)    mass per unit area = 4m/πR²
mass of disc of radius R/2 = (4m/πR²)×π(R/2)² = m
formula of moment of inertia of the disc = mr²/2
apply negative mass concept 
moment of inertia of remaining disc = moment of inertia of total disc - moment of inertia of removing disc 
                                                    = 4mR²/2 - m(R/2)²/2 
                                                    = 15mR²/8 
          hence option (b) is correct.

Answer 2

(2)    Mass per unit area = 4m/πR²
mass of disc of radius R/2 = (4m/πR²)×π(R/2)² = m
formula of moment of inertia of the disc = mr²/2
apply negative mass concept 
moment of inertia of remaining disc = moment of inertia of total disc - moment of inertia of removing disc 
                                                    = 4mR²/2 - m(R/2)²/2 
                                                    = 15mR²/8 
          hence option (b) is correct.