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


I assume L=120 yards as the length of the football field.
1) The average speed is given by the total distance covered by the player divided by the time taken.
The total distance covered to go from one goal line to the other and then back to the 40-yards line is

And the time taken is t=22.4 s, so the average speed of the player is

2) The find the average velocity, we should also consider the direction (and the sign) of the velocity.
In the the first part of the motion, the player goes from one goal line to the other one, so he covers 120 y. However, in the second part of the motion he goes back by 80 y. Therefore, the net displacement of the player is

and so, the average velocity is
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The average speed is determined by the following formula:
average speed = [sum of (speed * time for which that speed was traveled)] / total time
average speed = [(83 * 26 + 41 * 52 + 60 * 45 + 0 * 15) / 60] / [(26 + 52 + 45 + 15) / 60]
*note: The division by 60 is to convert minutes to hours. We see that the 60 cancels from the top and bottom of the division
average speed = 50.65 km/hr
The total distance traveled is equivalent to the numerator of the fraction we used in the first part. This is:
Distance = (83 * 26 + 41 * 52 + 60 * 45 + 0 * 15) / 60
Distance = 116.5 kilometers