Question

The graph above shows a superhero's linear acceleration over time.
At what point in time does the hero's VELOCITY reach a numerical minimum?

• A. $0.00s$
• B. $2.00s$
• C. $4.00s$
• D. $6.00s$
• E. $8.00s$

Answer 1

The correct option is C $4.00s$

Change in velocity is given by the area under the acceleration time graph.
Therefore if initially velocity is $v_o$, velocity at $t=4s$ is given by
$v_4=v_o+(areaunderthecurvefromt=0stot=4s)=v_o+(-1\times 4+\frac{1}{2}(-1)\times 2+(-1)\times 2+\frac{1}{2}\times (-2)\times 2=v_o-9$$
The velocity will keep on increasing after 4s till 8s.
Thus the velocity will reach a minimum at t=4s.