gravitation

q4 ans abc
doubt in b
since it is asking about total energy of planet we should take only kinetic energy in account
not the potential energy because potential energy is energy of sysytem not of single body


Yes it will the system energy but we take the potential energy of the planet with respect to sun
So, we need to take potential energy also for calculating total energy.
For example,
When we calculate the energy of a mass which is at a height h from ground
We say that its potential energy with respect to earth is mg(distance from earth) .