Question

a stone is thrown vertically upwards with a velocity of 20 ms-'.find the maximum height reached by the stone and the total time of flight

Answer 1

u=20m/s
v=0m/s
accleration is not given so we take 9.8m/s^ and it will be negative as it is in upward direction (opposite) .
a=-9.8m/s^2
v^2-u^2=2as
0^2-20^2=2×(-9.8)s
-400=-19.6s
400/19.6=s
s=20.4m
v=u+at
0=20+(-9.8)t
-20=-9.8t
20/9.8=t
2.0sec
total time is 2+2 =4 seconda