A car travels up a hill at a constant speed of 41 km/h and returns down the hill at a constant speed of 66 km/h. Calculate the average speed for the round trip.
Given :
Speed with which car travels up the hill , v1 = 41 km/h
Speed with which car travels down the hill, v2 = 66 km/h
For the round trip, average speed is given as :
v = total distance travelled / elapsed time
i.e. v = 2s/ (t1+t2) ............(1)
Where s is the distance it travels up or down the hill
t1 can be given as :
t1 = s/v1
And t2 can be given as
t2 = s/v2
putting values in equation (1) we get :
v = 2v1v2/(v1+v2)
i.e. v = 2(41)(66)/(41+66)
v = 50.58 m/s
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