An object is projected upward with a velocity of 100 m/sec. It will strike the ground in approximately

Let f be the time taken by the object to reach maximum height where v = 0. Hence,
0=100-10 x t₁ or t₁ = 10sec
Further, (0)² =(100)² -2 x 10 x h
or h= 500m
Let t₂ be the time taken by the object to strike the ground.
Then
$500=0\times {\mathrm{t}}_2+\frac{1}{2}\times 10\times {\mathrm{t}}_2^2 \mathrm{or} {\mathrm{t}}_2=10\sec$
Total time t =t₁ + t₂ = 20 sec