Question

For a particle moving in a straight line, the displacement of the particle at time $t$ is given by $S=t^{3}-6t^{2}+3t+7$ . The velocity of the particle when its acceleration zero is

• A. $-9 \, ms^{- 1}$
• B. $-12 \, ms^{- 1}$
• C. 3 $\, ms^{- 1}$
• D. 42 $ms^{- 1}$

Answer 1

Answer: (A)

$-9 \, ms^{- 1}$

Answer 2

$v=3t^{2}-12t+3;a=6t-12$ When $a=0,6t-12=0$ or $6t=12$ or $t=2$ s When $t=2$ s, $v=3\times 2\times 2-12\times 2+3=-9 \, ms^{- 1}$