MCQ
Velocity of a particle moving along a straight line is given by $v = t^2 -3t -4\,(m/s)$. Find the velocity at the instant when no net force is applicable on particle.......$m/s$
- A$-1.25$
- B$6.25$
- C$1.25$
- ✓$-6.25$
✓
Answer
Correct option: D.
$-6.25$
d
If Net force is zero, then its acceleration must
If Net force is zero, then its acceleration must
be zero at that instant
$v=t^{2}-3 t-4$
$a=\frac{d v}{d t}=2 t-3=0 \Rightarrow t=3 / 2$
at this time
$v=\left(\frac{3}{2}\right)^{2}-3\left(\frac{3}{2}\right)-4$
$=\frac{9}{4}-\frac{9}{2}-4=\frac{-25}{4} \mathrm{m} / \mathrm{s}$
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