Question

A car travels a distance of 2000m.If the first half distance is covered at 40 km/hr and the second half with speed v and the average speed is 48 km/hr then the value of v is

Answer 1

Time to cover first half = $\frac{1}{40} hrs$
Time to cover the second half = $\frac{1}{v} hrs$
Average speed = $\frac{Total distance}{Total Time} = \frac{2}{ \frac{1}{40} + \frac{1}{v} } =48\ (given)$

From the above equation v = 60 km/hr

Answer 2

1st half=1/40km/hr. 2nd half 1/v km/hr average speed=total distance/total time taken

Avg.speed=2/1/40+1/v. Given avg.velocity=48km/hr so solve them then we get 60 km/hr .. answer