Answer:
Maximum height is20m and time taken will be 2second
Explanation:
vi=20m/s
vf=0m/s
g=10m/s^2
Using third equation for objects falling freely
2gh=(vf)^2-(vi)^2
Putting values
2(10m/s^2)h=(0m/s)^2-(20m/s)^2
20h=400m
h=20m
Now we have to find the time
Using first equation of motion for objects falling down freely
vf=vi+at
substituting the equation
(vf-vi)/g=t
(0-20)/10=t
t=2second
