A stone is thrown vertically upward and distance, S metres after t seconds is given by S = 12t + \(\frac{5}{2t^2}\) - t\(^3\). Calculate the distance travelled in the third second.
A. 5.5m B. 14.5m C. 26.0m D. 30.0m
Correct Answer: A
Explanation
From S = 12t + \(\frac{5}{2t^2}\) - t\(^3\); Distance traveled in 2 seconds S = 12[2] + \(\frac{5}{2[2]^2}\) - 2\(^3\). = 24 + 10 - 8 = 26m Distance traveled in 3 seconds S = 12[3] + \(\frac{5}{2[3]^2}\) - 3\(^3\) = 36 + 22.5 - 27 = 31.5m Distance traveled in the 3rd second = 31.5m - 26m : S = 5.5m
