A stone is dropped from the top of the tower. Its speed after it has fallen 20 m is (Take g = 10 ms-2)
Here,
u = Initial velocity = 0
v = Final velocity
s = Distance travelled = 20 m
a = acceleration = g = 10 ms-2
Now, we know from the equations of motion that,
ms-1
v = 20 ms-1
Hence, option D is correct.