Question

A car moves a distance of 200 m. It covers the first half of the distance at speed 40 km/h and the second half of the distance at speed v. If the average speed is 48 km/h, then the value of v is

Answer 1

Let the speed of the car in the first half be V1

V 1= 40 km/hr

Let the speed of the car in the second half be V2

V 2 = ??

The average speed of the car in the entire journey is

V = 48 km/hr

As per the formula,

V avg = 2(V 1 × V 2 )/ V 1 + V 2

48. = 2 (40× V 2 ) / 40 + V 2

48. = 80 V 2 / 40 + V 2

1920 + 48 V 2 = 80 V 2

1920 = 38 V 2

V 2 = 1920/38

V 2 =50.52 km/hr