An auto travels the first halftime with a uniform speed u and the next halftime with a uniform speed v. Find its average speed.
Let T be the total journey time.
Step: Express total distance in terms of speed and time.
Total distance =d=d1+d2=(u× T2)+(v×T2)
d=T2(u+v)
Total time =T
Vav=dT
=T2(u+v)T
=u+v2