A body falling under gravity covers two points A and B separated by 80 m in 2 s . The distance of upper point A from the starting point is _____ m . Use g = 10 m s - 2

Step-by-step solution

From A → B , using the equation of motion, we have - 80 = - v 1 t - 1 2 × 10 t 2 ⇒ - 80 = - 2 v 1 - 1 2 × 10 × 2 2 ⇒ - 80 = - 2 v 1 - 20 ⇒ - 60 = - 2 v 1 ⇒ v 1 = 30 m s - 1 From O to A , it follows that v 2 = u 2 + 2 g S ⇒ 30 2 = 0 + 2 × ( - 10 ) ( - S ) ⇒ 900 = 20 S ⇒ S = 45 m