Question

Stone thrown vertically upward with speed of 20m/s how high will it go before it began to fall

Answer 1

u = 20m/s

v = 0m/s

Acceleration due to gravity is taken as negative. This is becaue, when the direction of motion of object is opposite to 'g', the "g" is taken as -ve.

Hence,

g=-9.8m/s^2

v^2 - u^2 = 2gh

0^2 - 20^2 = 2*-9.8*h

-400 = -19.6h

h = -400/-19.6

h = 400/19.6

h = 20.408 [Approximately].

HOPE IT IS CLEAR FOR YOU!!!