Question

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

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

Answer 1

Answer: (D)

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., $\upsilon =0$
$\therefore $ Impulse $=m\left(\upsilon-u\right)$
$=2\,kg\left(0-\frac{3}{4}m\,s^{-1}\right)=-\frac{3}{2}kg\,m\,s^{-1}$