When his speed reaches 16 ms^-1 he adopts a position for which the air resistance is 4kv^2 newtons. Find his new terminal speed (Did this as well, got 20m/s which is also correct).

Find also the acceleration with which he is falling (need help with both of these):

(a) just before he adopts the new position. (answer in book is 8.4m/s/s)

(b) just after he adopts the new position. (answer in book is 3.6m/s/s)

I have no idea how to go about solving (a) and (b). please help! (Happy)