Question

an object covers half the distance with the speed of 20m/s and other with a speed of 30m/s. Find the average speed

Answer 1

First half, time is d/20 
second half, time is d/30 
total time is (d/20) + (d/30) = d((1/20) + (1/30)) = d((3/60) + (2/60)) 
total time = d(5/60) = d/12 
total distance = 2d 
Average velocity = 2d/(d/12) = 24 m/s