Okay, here are the steps to solve this problem:
(a) To accelerate the car from rest to v0/2, the required work is proportional to the square of the final velocity.
So W = k*v^2 (where k is some constant)
Setting v = v0/2, the work required is:
W = k*(v0/2)^2 = k*v0^2 / 4
Therefore, the work required is W0/4
(b) To accelerate the car from v0/2 to v0, the required work is:
W = k*v^2 (where v starts at v0/2)
Setting v = v0, the work required is:
W = k*(v0/2)^2 * 2 = k*v0^2 / 2 = W0/2
Therefore,
(a) W0/4
(b) W0/2
Does this make sense? Let me know if you have any other questions!