A particle has initial velocity $(3 \hat{\mathrm{i}}+4 \hat{\mathrm{j}})$ and has acceleration $(0.1…
A particle has initial velocity $(3 \hat{\mathrm{i}}+4 \hat{\mathrm{j}})$ and has acceleration $(0.1 \hat{\mathrm{i}}+0.3 \hat{\mathrm{j}})$. Its speed after $10 \mathrm{~s}$ is
7 unit
$7 \sqrt{2}$ unit
8.5 unit
10 unit
Solution
From first equation of motion
$\begin{aligned}
\mathrm{v} & =\mathrm{u}+\mathrm{at} \\
\mathrm{v} & =3 \hat{\mathrm{i}}+4 \hat{\mathrm{j}}+10(0.4 \hat{\mathrm{i}}+0.3 \hat{\mathrm{j}}) \\
\mathrm{v} & =7 \hat{\mathrm{i}}+7 \hat{\mathrm{j}} \\
|\mathrm{v}| & =7 \sqrt{2}
\end{aligned}$