A car travels first 30 km with a uniform speed of 60 km h−1 and then next 30 km with a uniform speed of 40 km h−1. Calculate:
(i) the total time of journey,
(ii) the average speed of the car.
(i) Time taken for first part of the journey, t1=d1v1=3060 h=0.5 h
Time taken for second part of the journey, t2=d2v2=3040 h=0.75 h
Total time, t=t1+t2=0.5+0.75=1.25 h
(ii) Average speed=Total distanceTotal time=30+301.25=48 kmph