A car travels from a point A to B at a constant speed of 50 km/ h. On return along the same path it travels at a constant speed of 40 km/ h. Find its distance travelled, displacement and average speed.

Solution :

Let the distance between A and B is x 
First speed = 50 km/h
time = distance/time
t1 = x/50 
Return journey 
Speed = 40 km/h
t= x/40 
Total distance travelled = x + x => 2x 
Average speed = total distance/total time taken
=> 2x/(x/50 + x/40)
=> 2x/(40x + 50x/200)
=> 2x × 200/90x
=> 45 km/h
The displacement of the car will be zero because it comes back to its initial position.

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