Physics Two Dimensional Motion Question 141
Question: A particle has an initial velocity $ 3\hat{i}+4\hat{j} $ and an acceleration of $ 0.4,\hat{i}+0.3\hat{j} $ . Its speed after 10 sec is
Options:
A) 7$ \sqrt{2} $ units B) 7 units C) 8.5 units D)10 units
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Answer:
Correct Answer: A
Solution:
[a] $ \vec{u}=3\hat{i}+4\hat{j}\Rightarrow \text{u}x=3,\text{and },\text{uy=4} $ $ \vec{a}=0.4\hat{i}+0.3\hat{j}\Rightarrow \text{a}x=0.4,\text{and },\text{ay}=0.3 $ $ \text{So, }{{V _{x}}=ux+a _{x}t=3+0.4\times 10=3+4=7 $ . $ {{V _{y}}=\text{uy+}{{a _{y}}t=4+0.3\times 10=4+3=7 $ $ \vec{V}=7\hat{i}+7\hat{j} $
$ \Rightarrow ,|\vec{V}|,=\sqrt{7^{2}+7^{2}}=7\sqrt{2}\text{ units} $
BETA
