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 can’t understand I’m sorry but if you need help with math I can help you
Answer: 5,640 s (94 minutes)
Explanation:
the tangential speed of the HST is given by
(1)
where
is the length of the orbit
r is the radius of the orbit
T is the orbital period
In our problem, we know the tangential speed:
. The radius of the orbit is the sum of the Earth's radius and the distance of the HST above Earth's surface:

So, we can re-arrange equation (1) to find the orbital period:

Dividing by 60, we get that this time corresponds to 94 minutes.
Altitude is the angle measured above the horizon