Question

9. A ball is thrown vertically up from a point on
ground with speed u. At a same time other ball is
dropped from height h. Their relative acceleration
will be​

Answer 1

answer : relative acceleration = zero

explanation : The first ball is thrown vertically up and other ball is dropped vertically down, both are moving under the gravity. and we know, direction of acceleration due to gravity is always towards the centre of earth and value of it is g ≈ 9.8 m/s²

so, acceleration acting on both cases are same and e.g., g ≈ 9.8 m/s² [ if we assume height of 2nd ball , h is negligible comparing to radius of earth.]

so, relative acceleration = g - g = 0

hence, in case of motion under gravity, relative acceleration must be taken as zero.