Motion in a Straight Line - Result Question 12

12. A particle has initial velocity $(2 \vec{i}+3 \vec{j})$ and acceleration $(0.3 \vec{i}+0.2 \vec{j})$. The magnitude of velocity after 10 seconds will be :

[2012]

(a) $9 \sqrt{2}$ units

(b) $5 \sqrt{2}$ units

(c) 5 units

(d) 9 units

Show Answer

Answer:

Correct Answer: 12. (b)

Solution:

  1. (b) $\vec{v}=\vec{u}+\vec{a} t$

$v=(2 \hat{i}+3 \hat{j})+(0.3 \hat{i}+0.2 \hat{j})^{\prime} 10=5 \hat{i}+5 \hat{j}$

$|\vec{v}|=\sqrt{5^{2}+5^{2}}$

$|\vec{v}|=5 \sqrt{2}$