A body of mass $4 \mathrm{~kg}$ experiences two forces $\vec{F}_1=5 \hat{i}+8 \hat{j}+7 \hat{k}$ and $\overrightarrow{\mathrm{F}}_2=3 \hat{i}-4 \hat{j}-3 \hat{k}$. The acceleration acting on the body is :
Solution
<p>To find the acceleration acting on the body, we first need to determine the resultant force acting on the body by adding the two forces $\vec{F}_1$ and $\vec{F}_2$ vectorially. Then, we apply Newton's second law of motion, which states that the acceleration $\vec{a}$ of a body is directly proportional to the total force $\vec{F}$ acting on it and inversely proportional to the mass $m$ of the body :</p>
<p>$\vec{F} = m \cdot \vec{a}$</p>
<p>or</p>
<p>$\vec{a} = \frac{\vec{F}}{m}$</p>
<p>Let's start by adding the forces:</p>
<p>$$ \vec{F}_1 + \vec{F}_2 = (5 \hat{i}+8 \hat{j}+7 \hat{k}) + (3 \hat{i}-4 \hat{j}-3 \hat{k}) $$</p>
<p>Performing the addition component-wise:</p>
<p>$$
\vec{F}_{\text{total}} = (5 + 3)\hat{i} + (8 - 4)\hat{j} + (7 - 3)\hat{k} \
\vec{F}_{\text{total}} = 8 \hat{i} + 4 \hat{j} + 4 \hat{k}
$$</p>
<p>Now, let's use the formula for acceleration with $m = 4 \mathrm{~kg}$:</p>
<p>$$
\vec{a} = \frac{\vec{F}_{\text{total}}}{m} = \frac{8 \hat{i} + 4 \hat{j} + 4 \hat{k}}{4 \mathrm{~kg}}
$$</p>
<p>Divide each component by the mass:</p>
<p>$\vec{a} = 2 \hat{i} + 1 \hat{j} + 1 \hat{k}$</p>
<p>So, the acceleration acting on the body is:</p>
<p>$\vec{a} = 2 \hat{i} + \hat{j} + \hat{k}$</p>
<p>Thus, the correct option is:</p>
<p>Option A :
<br/><br/>$2 \hat{i}+\hat{j}+\hat{k}$</p>
About this question
Subject: Physics · Chapter: Laws of Motion · Topic: Newton's First Law
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