Question

Q.6 A car moves at a constant speed of \( 60 kmhr ^{-1} \) for half of the journey and \( 80 kmhr ^{-1} \) for remaining half of the journey. Find the average speed of the car.

Answer 1

Let the distance of total journey be d

So, speed till d/2 = 60km/hr

       speed after first half(d/2)= 80km/hr

Distance = speed × time

d/2 = 60t.            t= d/120

d/2 = 80t_1.            t₁= d/160

AVERAGE SPEED = TOTAL DISTANCE ÷ TOTAL TIME

=.                                      d

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                                d/120+d/160

.............= 480/7

=68.57