Everybody, when free, falls towards the centre of earth with an acceleration `= g`, which is called acceleration due to gravity. The value of `g` on the surface of earth is, `g = (GM)/(R^(2)) = 9.8 m//s^(2)`. It is a vector, directed always the centre of earth. The value of `g` does not depend upon shape, size or mass of the body. Rether, it depends on mass and size of earth (or planet due to which there is a gravity pull).
Read the above passesge and answer the following questions :
(i) A piece of stone and a feather are dropped together in space from the same height. which one will strike the ground first ? (ii) The mass of a planet is `(1)/(8)th` the mass of earth and its diameter is `(5)/(6)` the diameter of earth. What is the value of 'g' on the surface of this planet.
(iii) What does the concept of free fall imply in day to day life?

Explanation

(i) For both the stone and feather, `g` is same. Therefore, the two hit the ground together.
(ii) Here, `M' = (1)/(8)M, R' = (5)/(6), g' = ?`
`(g')/(g) = (M'//R'^(2))/(M//R^(2)) = (M')/(M) xx ((R )/(R'))^(2) = (1)/(8) xx ((6)/(5))^(2) = (36)/(200)`,
`g' = (36)/(200) xx g = (36)/(200) xx 9.8m//s^(2) = 1.76 m//s^(2)`
(iii) In day to day life, the concept of free fall inplies that unless we hole ourselves against the perverse attractions of the world, we would fall freely to new lows. The acceleration and speed of free fall will be same for anybody and everybody irrespective of their stature.