Question 1196122
.



        In the post by tutor @Shin, the answer to question  (a)  is correct,
        while the answer to question  (b)  is  INCORRECT.



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The correct answer to question (b) is

    the displacement of the particle in the fifth second is s(5) - s(4), 

    where  s(t) = {{{t^3/3}}} - {{{3t^2}}} + 2t.


So,  s(4) = {{{4^3/3}}} - {{{3*4^2}}} + 2*4 = -18.6667 m   (rounded),

     s(5) = {{{5^3/3}}} - {{{3*5^2}}} + 2*5 = -23.3333 m   (rounded),


and the displacement in the fifth second is

     s(5) - s(4) =  -23.3333 - (-18.6667) = -4.6666 m  (rounded).


<U>ANSWER</U> to (b)  is  -4.6667 m  (rounded).
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