Question

a particle moving in a straight line covers half the distance with speed of 3 metre per second quora

Answer 1

Answer:

Let the distance, for convenience of calculation, be 60 metres, so at 20 m/sec the first half (30 m) takes 1.5 seconds (30/20), the second half takes 1 second (30/30). Total time 2.5 seconds, total distance 60 metres (assumed), so average speed is 60/2.5; you work that out. The distance we assume is for convenience of calculation only and obviously cancels out. You would get the same result by assuming any convenient distance to work with or just call it "x".