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
waec 2021furthermathematics

The correct answer is A. 5.5m

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

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