A cyclist starts from rest, accelerates uniformly for 4s to reach 6ms−1, and then immediately moves at a constant speed of 6ms−1 for the next 4s. Which one of the following comparisons is correct?
(a) Average velocity in the whole 8s equals the instantaneous velocity at t=8s.
(b) Average velocity in the whole 8s is 3ms−1.
(c) Instantaneous velocity at t=2s is equal to the average velocity during the first 4s.
(d) Average velocity in the first 4s equals the instantaneous velocity at t=4s.