A quite tricky mechanics question

I'm stuck on part 2/3 of Q 10



And parts 2/3/4/5 on Q 15

Could anyone help me please :/

Question 10. If you have the answer for (i0 then for (ii) the power is halved.
Since we are asked for the acceleration immediately after the failure, the speed isstill8 so what is the forward thrust?
Use Newton's second law to find the acceleration
For (iii) We now have resistances=kv where k is a constant. so use 8k=2x10^6 to find the value of k, then equate the thrust from the one remaining engine to kv and solve for v

Thanks so much, you make it sound so easy hahahahaha