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Since a is a function of x, use \(a = v\dfrac{dv}{dx}\):

\(v\,dv = (100 - 3x^2)\,dx \Rightarrow \displaystyle\int_0^v v\,dv = \int_0^x (100 - 3x^2)\,dx\)

\(\dfrac{v^2}{2} = 100x - x^3\)

At x = 8 m: \(\dfrac{v^2}{2} = 800 - 512 = 288 \Rightarrow v^2 = 576\)

Answer: v = 24 m/s at x = 8 m.

Doubtly AI · 25 Oct 2026 AI-verified · Oct 2026 Report
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