Question

An automobile travels on a straight road for 55 km at 20 km/h. It then continues in the same direction for another 60 km at 55 km/h. What is the average velocity (km/h) of the car during the full 115 km trip

Answer 1

Given :

Speed of automobile for first 55 km , $v_1=20\ km/h$ .

Speed of automobile for first 60 km , $v_2=55\ km/h$ .

To Find :

Average velocity of the full trip .

Solution :

We know , average velocity is given by :

$v_{avg}=\dfrac{\text{Total distance covered}}{\text{Total time taken }}$

Now , time is given by :

$T=\dfrac{D}{v}$

So ,

$v_{avg}=\dfrac{55+60}{\dfrac{55}{20}+\dfrac{60}{55}}\\\\v_{avg}=29.94\ km/h$

Therefore , the average velocity (km/h) of the car during the full 115 km trip is 29.94 km/h .

Hence , this is the required solution .