Answer the following questions related to the concept of escape velocity.
(i) Define the term escape velocity of a body from the surface of a planet.
(ii) The gravitational potential energy U of a body at a distance r from the centre of Earth is taken to be negative. State the reason for assigning this negative sign.
(iii) Explain why the total mechanical energy of a body is chosen to be zero when it is at an infinite distance from the attracting planet.