Answer:
Avoid downed power lines and stay away from buildings and bridges from which heavy objects might fall during an aftershock. Stay away until local officials tell you it is safe. A tsunami is a series of waves that may continue for hours. Do not assume that after one wave the danger is over.
Explanation:
Formula to calculate angular acceleration is as follows.

or, 
Putting the given values into the above formula as follows.

=
= 0.326 
Thus, we can conclude that the wheel’s angular acceleration if its initial angular speed is 2.5 rad/s is 0.326
.
The velocity will change (increase) by 9.8 m/s every second.
Why?
Since the ball is accelerated downward at
we can see that the ball is on "free fall". It means that the wall was dropped with no initial speed.
Now, if we want to know by how many meters per second does the object's velocity change every second, we need to understand the units of the acceleration. Let's write the equation of acceleration for better understanding.

So, from the equation we can see that the acceleration is changing the velocity every second.
Hence, if an object has the given acceleration (acceleration due to gravity, 9.8m/s2), it means that its speed will change (increase) by 9.8m/s every second.
Have a nice day!