Question

A particle has an initial velocity of $3\hat{i}+4\hat{j}$ and an acceleration of $0.4\hat{i}+0.3\hat{j}$. Its speed after $10$ s is?

• A. $7$ units
• B. $8.5$ units
• C. $10$ units
• D. $7\sqrt{2}$ units

Answer 1

Answer: (A)

$7$ units

$\begin{array}{c}InitialVelocity=3\hat{i}+4\hat{j}\\ Acceleration=0.4\hat{i}+0.3\hat{j}\\ Aswethat\\ \Rightarrow \frac{V-u}{t}=a\\ \Rightarrow \frac{V-\left(3\hat{i}+4\hat{j}\right)}{10}=0.4\hat{i}=0.3\hat{j}\\ \Rightarrow V-3\hat{i}-4\hat{j}=4\hat{i}+3\hat{j}\\ V=7\hat{i}+7\hat{j}\end{array}$