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
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Answer:
Correct Answer: 12. (b)
Solution:
- (b) $\vec{v}=\vec{u}+\vec{a} t$
$v=(2 \hat{i}+3 \hat{j})+(0.3 \hat{i}+0.2 \hat{j})^{\prime} 10=5 \hat{i}+5 \hat{j}$
$|\vec{v}|=\sqrt{5^{2}+5^{2}}$
$|\vec{v}|=5 \sqrt{2}$
