# For a particle moving in a straight line, the displacement of the particle at time 𝑡 is given by 𝑆 = 𝑡 3 − 6𝑡 2 + 3𝑡 + 7. What is the velocity of the particle when its acceleration is zero?

Question : For a particle moving in a straight line, the displacement of the particle at time 𝑡 is given by 𝑆 = 𝑡 3 − 6𝑡 2 + 3𝑡 + 7. What is the velocity of the particle when its acceleration is zero?

(A) $-9ms^{-1}$

(B) $-12ms^{-1}$

(C) $3ms^{-1}$

(D) $42ms^{-1}$