Question

a motorist travels 160 km hour and 160 km at 100 km/h. what is the average speed of the motorist for the trip?

Answer 1

Average speed is $v = \frac{L}{t}$, where $L$ is the total distance covered, and $t$ is the time it took to cover it.

During the first part, the distance covered is $L_1 = 160km$, and the time is $t_1 = 1 h$.

During the second part, the distance covered is $L_2 = 160 km$, and the time is $t_2 = \frac{L_2}{v_2}$, where $v_2 = 100 \frac{km}{h}$. Hence, average speed is:

$v = \frac{L_1 + L_2}{t_1 + t_2} = \frac{L_1+L_2}{t_1 + \frac{L_2}{v_2}} \approx 123.1 \frac{km}{h}$.