Can please explain

For (iii)
Why it is not
14-2=12
Why it is not counted from t=0?
Thank you

For part III, the question ask about the distance traveled by the particle at the fourth second, this means that we only need to account for the distance traveled between t=3 to t=4. Hence, we just need to focus on the positions of the particle when t= 3 and t=4, and find the distance between these two positions,provided that there's no U-turn during the time interval. If there's a U turn, it is something similar to part iv.

Wah. Kind of English comprehension. Understand (iv)
Well, For (iii) , it sld be interpreted in this way. Thx a lot.

There's a difference between fourth second and first four second, so yea need to be careful

Yes. Understand now. V easy to fall in the trap... Thanks again.