Answer:
a) 
b) The second runner will win
c) d = 10.54m
Explanation:
For part (a):

For part (b) we will calculate the amount of time that takes both runners to cross the finish line:


Since it takes less time to the second runner to cross the finish line, we can say the she won the race.
For part (c), we know how much time it takes the second runner to win, so we just need the position of the first runner in that moment:
X1 = V1*t2 = 239.46m Since the finish line was 250m away:
d = 250m - 239.46m = 10.54m
We can't tell without more information. We know it will be higher than 40 and lower than 75, but we don't know exactly where it will settle. In order to work that out, we would need to know the volumes of the water and the cube, and WHAT metal the cube is made of.
did you mean what activities are performed during the cool down?