A car with an initial velocity of 3 m/s has a velocity of 34 m/s after 3 sec. How far it moves in its third second of motion?

acceleration V=U + at a = 10.3 m/s^2

x = ut + 1/2 a t^2

x = 3 (3) + 1/2 (10.3) (3x3)

x = 56.25 m

but answer in book = 29 m ??


closed as off-topic by John Rennie, Danu, user10851, ACuriousMind, Kyle Kanos Sep 27 '14 at 11:35

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  • 1
    $\begingroup$ "in its third second", not in three seconds $\endgroup$ – 299792458 Sep 27 '14 at 9:32

Like New_new_newbie said, the question asks you to find the distance travelled in its third second (from t=2 to t=3 seconds). So just find x(2) and x(3), and the difference should give you 29m.

  • $\begingroup$ yes, thank you x(2) = 26.67 m, x(3) = 55.5, x(3) - x(2) = 29m $\endgroup$ – harry Sep 27 '14 at 9:39

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