Velocity of a particle moving along a straight line is given by v = t^2 -3t -4,(m/s) . velocity at i

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2.Motion in Straight Line

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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

$1.25$

D

$-6.25$

Solution

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

$v=\left(\frac{3}{2}\right)^{2}-3\left(\frac{3}{2}\right)-4$

$=\frac{9}{4}-\frac{9}{2}-4=\frac{-25}{4} \mathrm{m} / \mathrm{s}$

Standard 11

Physics

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