A particle moving in a straight line covers half the distance with speed of `3 m//s`. The half of the distance is covered in two equal intervals with speed of `4.5 m//s and 7.5 m//s` respectively. The average speed of the particle during this motion is :

Options

A. 4.0 m/s
B. 5.0 m/s
C. 5.5 m/s
D. 4.8 m/s

Answer

A

Explanation

Av. Speed `= ("Total distance")/("Total time")`

Av. Speed `= [(s)/(((s//2)/(3)) + t_(2))]`
For 1 st half `(s)/(2) = 3 xx t_(1)`
For 2nd half `(s)/(2) = 4.5 xx (t_(2))/(2) + 7.5 (t_(2))/(2)`