Question

A body travel a distance of 10 km with constant speed of 30 km/h and then the next 40 km at a constant speed of 50 km/h . Find the average speed for the whole journey.

Answer 1

Given :

▪ A body travels a distance of 10km at a constant speed of 30kmph.

▪ Then the 40km at a constant speed of 50kmph.

To Find :

▪ Average speed of body.

Concept :

☞ Average speed is defined as the ratio of total distance travelled to the total time taken.

☞ It is a scalar quantity.

☞ It has only magnitude.

☞ It can't be negative or zero.

☞ SI unit : m/s

Calculation :

→ Vav = (d1+d2)/(t1+t2)

→ Vav = (d1+d2)/[(d1/V1+d2/V2)]

→ Vav = (10+40)/[(10/30)+(40/50)]

→ Vav = 50/(0.33+0.8) = 50/1.13

→ Vav = 44.24kmph