Answer:
The final speed of the ball is 9 m/s.
Step-by-step explanation:
We have,
A steel ball is dropped from a diving platform. It is required to find the velocity of the ball 0.9 seconds after its released. It will move under the action of gravity. Using equation of motion to find it as :

u = 0 (at rest), a = g

So, the final speed of the ball is 9 m/s.