The figure shows the position - time $(x-t)$ graph of one-dimensional motion of a body of mass $0.4…

The figure shows the position - time $(x-t)$ graph of one-dimensional motion of a body of mass $0.4 \mathrm{~kg}$. The magnitude of each impulse is
  1. $0.4 \mathrm{Ns}$
  2. $0.8 \mathrm{Ns}$
  3. $1.6 \mathrm{Ns}$
  4. $0.2 \mathrm{Ns}$

Solution

From the graph, it is a straight line so, uniform motion. Because of impulse direction of velocity changes as can be seen from the slope of the graph. $ \begin{aligned} & \text { Initial velocity }=\frac{2}{2}=1 \mathrm{~m} / \mathrm{s} \\ & \text { Final velocity }=-\frac{2}{2}=-1 \mathrm{~m} / \mathrm{s} \\ & \qquad \bar{P}_{\mathrm{i}}=0.4 \mathrm{~N}-\mathrm{s} \\ & \qquad \overline{\mathrm{P}}_{\mathrm{i}}=-0.4 \mathrm{~N}-\mathrm{s} \\ & \overrightarrow{\mathrm{J}}=\overline{\mathrm{P}}_{\mathrm{i}}-\overline{\mathrm{P}}_{\mathrm{i}}=-0.4-0.4=-0.8 \mathrm{~N}-\mathrm{s}(\overrightarrow{\mathrm{J}}=\text { impulse }) \\ & |\overrightarrow{\mathrm{J}}|=0.8 \mathrm{~N}-\mathrm{s} \end{aligned} $

Asked in: JEE Main 2010

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