Question

plzz help ............

Answer 1

Let total distance = 2s
Time taken to cover half distance is = s/3

Let the distance covered by using 4.5 m/s velocity  = s1...
and let the distance covered by using 7.5  = s2

As it travels by 4.5 and 7.5 for equal intervals ( say t )

t = s1/4.5= s2/7.5 => s1= 0.6s2

Now ;
S1+s2= s
=> s2= s/1.6

=> t = s/(1.6×7.5)

Then the total time taken for the rest half distance = 2t = s/6

Avg velocity = 2s/(s/3 + s/6) = 4m/s