Question

A truck travels some distance with constant speed of 30km h-1 and returns back with the constant speed of 40km h-1 . Calculate the average speed of the truck

Answer 1

▶ Solution :

Given :

A truck travels first half of the total distance with speed 30kmph and second half of the total distance with speed 40kmph.

To Find :

Average speed of the truck.

Concept :

▪ Average speed is defined as ratio of total distance covered to the total time taken.

▪ If body covers first half half of total distance with speed X and second half of total distance with speed Y then average speed of body is given by

$\boxed{\bf{\pink{V_{av}=\dfrac{2XY}{X+Y}}}}$

Calculation :

$\implies\sf\:V_{av}=\dfrac{2(30)(40)}{30+40}\\ \\ \implies\sf\:V_{av}=\dfrac{2400}{70}\\ \\ \implies \boxed{\bf{\purple{V_{av}=34.28\:kmph}}}$