Question

a boy walks to his school at a distance of 6km with a constant speed of 25km/h and walk back with a constant speed of 4km/h his average speed expressed in km/h​

Answer 1

Answer:

A boy walks to his school at a distance of 6km with a constant speed of 25km/h and walks back with a constant speed of 4km/h his average speed is 6.89km/h

Explanation:

• The average speed is the total distance divided by the total time taken to cover that distance

       ⇒average distance= total distance /total time

• The speed of a body that covered distance (d) in a time interval (t) is

        $v=d/t$

From the question, we have

the distance to school from home $d=6km/h$

the speed of the boy to school from home $v_{1} =25km/h$

time taken to reach the school $t_{1} =d/v_{1}$

⇒$t_{1} =6/25=0.24s$

the speed of the boy from school to home $v_{2} =4km/h$

time of this travel is $t_{1} =6/4=1.5s$

now the average speed is $V=\frac{d+d}{t_{1}+ t_{2} }$

⇒$V=12/1.74=6.89km/h$