Question

particle moving in a straight linr covers half of the total distance with a speed of 3m/s. The other half of the distance is covered in two equal time intervals with speeds of 4.5 m/s and 7.5 m/s. the average speed of the particle during this motion is?

Answer 1

Let D be the distance.
Time taken in covering distance D/2 (t1) = D/2*3 =D/6 seconds
Time taken in covering distance D/4 (t2) = D/2*4.5 =D/18 seconds
Time taken in covering distance D/4 (t3) = D/2*7.5 =D/30 seconds
Total time = D/6 + D/18 + D/30 =23/36 D
Average speed = total distance/total time taken
Average speed=36/23 seconds