Question

A car covers first 50 km at the speed of 45 km/h and the next 50 km at the speed of 90 km/h. Find the average speed of the car in km/h.

Answer 1

Answer:

The average velocity is 67.5 km/h.

Explanation:

The average speed of the car is given by the formulae :

Avg velocity = $\frac{v_{1}+v_{2} }{2}$

                      = 45 + 90 /2

                      = 67.5 km/h

Answer 2

Given :-

A car covers first 50km at the speed of 45kmph and the next 50km at the speed of 90kmph.

To Find :-

Average speed of car during whole journey.

Concept :-

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

Calculation :-

If body covers first half of total distance with velocity V1 and secobd half of total distance with velocity V2, then average velocity of body is given by

$\implies\bf\pink{V_{av}=\dfrac{2V_1V_2}{V_1+V_2}}\\ \\ \implies\sf\:V_{av}=\dfrac{2(45)(90)}{45+90}\\ \\ \implies\sf\:V_{av}=\dfrac{8100}{135}\\ \\ \implies\boxed{\bf{\purple{V_{av}=60\:kmph}}}$