Question

A car travels half the distance with constant velocity of $40kmph$ and the remaining half with a constant velocity of $60kmph$. The average velocity of the car in $kmph$ is

• A. $40$
• B. $45$
• C. $48$
• D. $50$

Answer 1

The correct option is C

$48$

Explanation for the correct option:

Let the total distance travelled be $2x$

Time taken in travelling the first half of the distance $x$will be $t_1=\frac{x}{40}$

and the time taken in travelling the second half of the distance $x$will be $t_2=\frac{x}{60}$

Now the average velocity can be calculated as $V=\frac{totaldis\tan ce}{totaltime}$

$$\begin{gathered} =\frac{2x}{t_1+t_2} \\ =\frac{2x}{{\displaystyle \frac{x}{40}+\frac{x}{60}}} \\ =\frac{2x}{\left({\displaystyle \frac{5x}{120}}\right)} \\ =48kmph \end{gathered}$$
Hence, option C is correct.