Arnold K H Tan's answer to fifahhh's Secondary 4 Physics Singapore question.

done {{ upvoteCount }} Upvotes
clear {{ downvoteCount * -1 }} Downvotes
Arnold K H Tan
Arnold K H Tan's answer
2163 answers (A Helpful Person)
1st
The more realistic, but long answer: given a distance of 800m, the flash from the firing of pistol may not be clearly seen. There is a short delay before the smoke is ejected and forms a visible cloud. Thus, the timekeeper may inadvertently start the stopwatch later than expected.