1: A system is collection of two or more objects but how ca we define an object suppose if we talk about a tennis ball its an object but at atomic level we can say it is a system because it is made of millions of atoms and each atom can be considered as an object
3: The internal energy of a system is identified with the random, disordered motion of molecules; the total (internal) energy in a system includes potential and kinetic energy. ... It is the sum of all the microscopic energies such as: translational kinetic energy. vibrational and rotational kinetic energy
