Question

The position-time graph of a body of mass $2kg$ is as shown in figure. What is the impulse on the body at $t=0$ and $t=4$ s ?

• A. $\frac{2}{3}kgm{s}^{-1}$
• B. $-\frac{2}{3}kgm{s}^{-1}$
• C. $\frac{3}{2}kgm{s}^{-1}$
• D. $-\frac{3}{2}kgm{s}^{-1}$

Answer 1

Answer: (D)

$-\frac{3}{2}kgm{s}^{-1}$

At t=4 s, the body has constant velocity $u=\frac{3}{4}m{s}^{-1}$.
After t=4 s, the body is at rest i.e. v= 0
$\therefore$ Impulse = m(v-u)=$2kg(0-\frac{3}{4}m{s}^{-1})=-\frac{3}{2}kgm{s}^{-1}$