Question

On a 100km road, a car travels the first 50km at uniform speed of 30km/h. How fast must the car travel for the next 50 km so as to have an average speed of 45km/h for the entire journey.

Answer 1

s=100km
u=30km/hr
average velocity=45km/hr
therefore value of v is :
average velocity=(v+u)/ 2
45=(v+30)/2
90=v+30
60=v
therefore car travels at the speed of 60 km/hr
for next 50 km