Question

The magnitude of the impulse developed by a mass of $0.2$kg which changes its velocity from $5\hat{i}+3\hat{j}+7\hat{k}$ m/s to $2\hat{i}+3\hat{j}+\hat{k}$

• A. $2.7$N-s
• B. $1.3$N-s
• C. $0.9$N-s
• D. $3.6$N-s

Answer 1

The correct option is B $1.3$N-s

Given,

$m=0.2kg$

${\overrightarrow{v}}_i=5\hat{i}+3\hat{j}+7\hat{k}$

${\overrightarrow{v}}_f=2\hat{i}+3\hat{j}+\hat{k}$

Impulse, $I=m({\overrightarrow{v}}_i-{\overrightarrow{v}}_f)$

$\overrightarrow{I}=0.2\left[\right(5\hat{i}+3\hat{j}+7\hat{k})-(2\hat{i}+3\hat{j}+\hat{k}\left)\right]$

$\overrightarrow{I}=0.2(3\hat{i}+0\hat{j}+6\hat{k})$

Magnitude, $|\overrightarrow{I}|=0.2\sqrt{3^2+0^2+6^2}$

$I=1.3Ns$

The correct option is B.