Q5 (a) Answer the following :
(a) The casing of a rocket in flight burns up due to friction. At whose expense is the heat energy required for burning
      obtained? The rocket or the atmosphere?


Answers (1)

The total energy is given by :

                                        E\ =\ K.E\ +\ P.E

or                                           =\ \frac{1}{2}mv^2\ +\ mgh

The burning of casing results in a reduction in the mass of the rocket. This leads to a lowering in the total energy.

Thus heat required for burning is obtained from the expenses of the rocket.