I do not know the difference between "static" friction and "sliding" friction as I am a beginner of Physics.
What is it?
But I know that, as long as I understand from this textbook, this coefficient of friction applies to the friction acting in the opposite direction of the movement of the object. So I guess that you can use it for "sliding" friction.
Also I am not sure what you really want to imply when you say "at 35 seconds, the tension in the cable is 14000 N. AT 40 seconds, it is 16000 N. Because it increases linearly you can use the average value 15000 N for the entire 5 seconds".
But can we use the momentum formula for this question?
As you say, the difference in tensions is 16000  14000 = 2000
So the average would be 2000/2 = 1000
Then use the formula Ft = mv  mu where F = 1000, t = 5, m = 2000, u = 0,
So 1000*5 = 2000v  2000*0
v = 5000/2000 = 2.5 ms^(1)
Is that what you wanted to imply or something else?
