Question

distance between Delhi and Agra is 200 km, cover first half distance with speed of 50 km per hour what will be the speed of car in next half so the average speed becomes 60 km per hour

Answer 1

Given :-

▪ Distance b/w delhi and agra = 200km

▪ Car covers first half of total distance with speed 50kmph.

▪ Average speed of body during whole journey = 60kmph

To Find :-

▪ The speed of car in next half of total distance.

Concept :-

→ Average speed of body is defined as ratio of total distance to the total time.

→ Average speed is a scalar quantity.

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

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

Calculation :-

$\implies\sf\:60=\dfrac{2(50)(Y)}{50+Y} \\ \\ \implies\sf\:3000+60Y=100Y\\ \\ \implies\sf\:40Y=3000\\ \\ \implies\sf\:Y=\dfrac{3000}{40}\\ \\ \implies\boxed{\bf{\purple{Y=75\:kmph}}}$