Question

A car travels from stop A to stop B with speed of 30km per hour and then returns back to A with a speed of 50 km per hour find displacement of the car

Answer 1

Let the distance from A to B be x.

Then displacement of the car when it comes back to the same position is zero.

But the distance travelled is 2x.

Time taken by the car when it moves from A to B is given by

t1 = Distance/Speed = x/30

Time taken by the car when it moves from B to A,

t2 = Distance/Speed = x/50

Total distance = 2x

Total time = t1 + t2 = x/30 + x/50 = (5x + 3x)/150 = 8x/150

So, Average speed = Total distance/Total time = 2x/(8x/150) = 37.5 km/hr