A person travelling on a straight line moves with a uniform velocity $v_1$ for a distance $x$ and with a uniform velocity $v_2$ for the next $\frac{3}{2} x$ distance. The average velocity in this motion is $\frac{50}{7} \mathrm{~m} / \mathrm{s}$. If $v_1$ is $5 \mathrm{~m} / \mathrm{s}$ then $v_2=$ __________ $\mathrm{m} / \mathrm{s}$.
Answer (integer)
10
Solution
<p>To find the average velocity given the motion of a person traveling along a straight line with two different velocities, we start by calculating the average velocity ($ v_{\text{avg}} $) using the total distance traveled divided by the total time taken.</p>
<p>The distances and velocities are given as follows:</p>
<p><p>Distance $ x $ at velocity $ v_1 = 5 \, \text{m/s} $</p></p>
<p><p>Distance $ \frac{3}{2}x $ at velocity $ v_2 $</p></p>
<p>The formula for average velocity is:</p>
<p>$ v_{\text{avg}} = \frac{\text{Total Distance}}{\text{Total Time}} $</p>
<p>Given:</p>
<p>$ v_{\text{avg}} = \frac{50}{7} \, \text{m/s} $</p>
<p>The total distance traveled is:</p>
<p>$ x + \frac{3x}{2} = \frac{5x}{2} $</p>
<p>The time taken to cover each segment is given by:</p>
<p><p>Time for $ x $: $ t_1 = \frac{x}{v_1} = \frac{x}{5} $</p></p>
<p><p>Time for $ \frac{3x}{2} $: $ t_2 = \frac{\frac{3x}{2}}{v_2} = \frac{3x}{2v_2} $</p></p>
<p>Now, using the formula for average velocity:</p>
<p>$ \frac{50}{7} = \frac{\frac{5x}{2}}{\frac{x}{5} + \frac{3x}{2v_2}} $</p>
<p>Simplifying the equation:</p>
<p>$ \frac{50}{7} = \frac{5/2}{\frac{1}{5} + \frac{3}{2v_2}} $</p>
<p>Cross-multiplying gives:</p>
<p>$ \frac{1}{5} + \frac{3}{2v_2} = \frac{7}{20} $</p>
<p>Solving for $ \frac{3}{2v_2} $:</p>
<p>$ \frac{3}{2v_2} = \frac{7}{20} - \frac{1}{5} = \frac{7-4}{20} = \frac{3}{20} $</p>
<p>Finally, solving for $ v_2 $:</p>
<p>$ \frac{3}{2v_2} = \frac{3}{20} $</p>
<p>$ v_2 = 10 \, \text{m/s} $</p>
<p>Thus, the value of $ v_2 $ is $ 10 \, \text{m/s} $.</p>
About this question
Subject: Physics · Chapter: Kinematics · Topic: Motion in a Straight Line
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