M2 Paper 5 math mechanics

[nour1234]

Hi, I reallllly don't understand questions 5ii) and 6iii) if ANYONE can help please do.


this is the question paper http://www.xtremepapers.me/CIE/International A And AS Level/9709 - Mathematics/9709_w10_qp_53.pdf


for 5ii) can someone just please write down the steps of the answer with explanation? I got v=0.45 which is wrong

And for 6iii) I don't understand why we just dont substitute our value of T (that we found in ii)) into the equation, why do we have to diffrentiate and make a whole new diffrential equation?

Thanks for any responses!

 

[nour1234]

I figured out 5ii), it was a simple miscalculation... but I can't for the life of me figure out 6iii).....only question on the exam I can't do