Question

A boat of mass 300 kg moves according to the equation x = 1.2 t² – 0.2 t³. When the force will become zero?

• A. 2s
• B. 1 s
• C. 6s
• D. 2.8 s

Answer 1

Answer: (A)

2s

Answer 2

$\frac{dx}{dt} = 2.4t - 0.6t^{2}$ and

$\frac{d^{2}x}{dt^{2}} = 2.4 - 1.2t = 0$or t = 2s.