Given, initial velocity of the ball (u) = 0 (since it began at the rest position)
Distance traveled by the ball (s) = 20m
Acceleration (a) = 10 ms-2
By third motion equation, \( v^2 - u^2 = 2 a s \)
= 2×(10)×(20) + 0
v2 = 400
Therefore, v= 20m/s
The ball hits the ground with a velocity of 20 meters per second.
By first motion equation, \( v = u + at \)
Therefore, \( 20 = 0 + 10 t \)
\(\Rightarrow \) t = 2 seconds
Therefore, the ball reaches the ground after 2 seconds.