Question

The initial velocity of a particle is $\overrightarrow{u}=4\hat{i}+3\hat{j}$. It is moving with uniform acceleration $\overrightarrow{a}=0.4\hat{i}+0.3\hat{j}$. Its speed after $10$ seconds is

• A. $3$ units
• B. $4$ units
• C. $5$ units
• D. $10$ units

Answer 1

The correct option is D $10$ units

$\overrightarrow{V_x}=\overrightarrow{u_x}+\overrightarrow{a_x}t$
$\overrightarrow{V_x}=4\overrightarrow{i}+\left(0.4\overrightarrow{i}\right)\times 10=8\overrightarrow{i}$m/s
$\overrightarrow{V_y}=\overrightarrow{u_y}+\overrightarrow{a_y}t$
$=3\overrightarrow{j}+\left(0.3\overrightarrow{j}\right)\times 10=6\overrightarrow{j}$m/s.

$V_{net}=\sqrt{V_x^2+V_y^2}=\sqrt{8^2+6^2}$ $=10$ m/s