How much energy is required by a satellite to keep it orbitting? Neglect air resistance.

How much energy is réquired to ionise a 'H' atom if the electron occupies 'n=5' orbit? Compare your answer with the ionisation enthalpy of 'H' atom (energy required to remove the electron from 'n=1' orbit).

An object released near the surface of the earth is said to be in free fall.(Neglect the air resistance). Choose the correct alternative from the clues given at the end of the statement. "Free fall is an example of __________ accelerated motion."(uniformly/nonuniformly).

Consider a body falling freely through the atmosphere. Neglecting the air resistance prove that the total mechanical energy of the body remains constant throughout the fall.