A stone is thrown vertically upward and distance, S metres after t seconds is given...
FURTHER MATHEMATICS
WAEC 2021
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 maximum height reached.
- A. 418.5m
- B. 56.0m
- C. 31.5m
- D. 30.0m
Correct Answer: C. 31.5m
Explanation
S = 12t + \(\frac{5}{2t^2}\) - t\(^3\);
ds/dt = 12 + 5t - 3t\(^2\)
At max height ds/dt = 0
i.e 12 + 5t - 3t\(^2\)
(3t + 4)(t -3) = 0;
t = -4/3 or 3
Hmax = 12[3] + \(\frac{5}{2[3]^2}\) - 3\(^3\)
= 36 + 45/2 - 27
= 31.5m
Post an Explanation Or Report an Error
If you see any wrong question or answer, please leave a comment below and we'll take a look. If you doubt why the selected answer is correct or need additional more details? Please drop a comment or Contact us directly. Your email address will not be published. Required fields are marked *