Question

A particle moves along x-axis with speed 6 m/s for the first half distance of a journey and the second half distance with a speed 3 m/s. The average speed in the total journey is (1) 5 ms/ (2) 4.5 m/s (3) 4 m/s (4) 2 m/s

Answer 1

let the dist be 2x
1st half
dist =x
speed is 6m/s
s=d/t
t=d/s=x/6

2nd half
dist x
speed is 3m/s
time =d/s=x/3

average speed=total dist /total time
=x+x/(x/6)+(x/3)
=2x/3x/6
=2x*6/3x
=4m/s

Answer 2

Hope you understand