Question

The velocity time graph of a particle moving along a straight line has the form of a parabola

$v=t^2$-$6t$+$8$ m/s. Find acceleration (in $m/s^2$) when velocity is equal to zero :

• A. $2$
  
• B. $-2$
  
• C. $1$
  
• D. $-1$
  

Answer 1

Answer: (A), (B)

The correct options are
A $2$
B $-2$

Here, velocity $v=t^2-6t+8$

So, acceleration, $a=\frac{dv}{dt}=2t-6$

When velocity is zero, $t^2-6t+8=0$ or $t=\frac{6\pm \sqrt{6^2-4\left(1\right)\left(8\right)}}{2\left(1\right)}$ or $t=4,2$

When $t=4,$ $a=2\left(4\right)-6=2$ and for $t=2$ , $a=2\left(2\right)-6=-2$