Answer:
The velocity just before hitting the ground is 
Explanation:
From the question we are told that
The initial speed is 
The final speed is 
From the equations of motion we have that

Where s is the distance travelled which is the height of the cliff
So making it the subject of the the formula we have that

Where a is the acceleration due to gravity with a value 
So


Now we are told that was through horizontally with a speed of

Which implies that this would be its velocity horizontally through out the motion
Now it final velocity vertically can be mathematically evaluated as

Substituting values


The resultant final velocity is mathematically evaluated as

Substituting values


True, all of those careers go in the same category
Let's call this "certain amount" with a variable, x, (since it's not specified in the question, I will assume that the answer shall just be based on this variable).
So every additional floor will make the building sink by x, and let's make the unit cm, so x cm.
Now we know that the maximum depression is 20 cm, and it is also
x*y, where y is the number of floors.
So we have x*y=20,
therefore the number of floors is:
20/x or This is the answer
I think the correct answer from the choices listed above is option D. Solar cells convert electromagnetic energy into electrical energy. This is because the photons from the rays of light are electromagnetic waves or particles. Hope this answers the question.
V = p / m
V = 1000 / 2.5
V = 400 m/s
hope this helps!