Position of a moving body?

15. A car travels a certain distance with a speed of 50 km. p. h. and retums with a

speed of 40 km. p. h. Calculate the average speed for the whole journey. (Hint

Suppose that the certain distance travelled by the car with a speed of 50 km/h

is x so that he total distance travelled becomes x + x = 2x)

44.4 kmp. h

Explanation:

Take car is going x distance with. And will come back same distance x There for, time taken to going can be taken as t1

t1 = Distance / Speed

t1 = x / 50 h

time taken to come back can be taken as = t2

t2 = Distance / Speed

t2 = x / 40 h

Average speed = Total distance travel by the car / total time

= 2x / (x/50 + x/40)

= 2 * 50*40 / (90)

= 44.4 kmp. h