The bus moves for 20 seconds in a straight line to the stop, passing a distance of 310 m. Its initial speed is 15 \frac{m}{s}. Prove that the velocity of the bus changes in direction.

Solutions of Savchenko Problems in Physics

Aliaksandr Melnichenka
October 2023

    <h3 id="back-link"><a href="/#1.2">$\leftarrow$Back</a></h3>

    <h3> Statement </h3>
    <p>
        $1.2.7.$ The bus moves for $20$ seconds in a straight line to the stop, passing a distance of $310$ m. Its initial speed is $15$ $\frac{m}{s}$. Prove that the velocity of the bus changes in direction.
    </p>

    <h3>Solution</h3>
    <p>
        Since the bus comes to a complete stop at the end, the average speed is

$$v_\text{average}=\frac{15+0}{2} \frac{m}{s}=7.5 \frac{m}{s}$$
If there is an equal-accelerated motion, then the body must travel a path
$$s = v_\text{average}\cdot t=150\text{ m}$$
Whence it follows that the body has accelerated, but the motion is not equal-accelerated

    <h4>Answer</h4>
    <p>
        The average velocity is greater than the initial velocity and the final velocity is zero.
    </p>


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