A body travelling with uniform acceleration crosses two point `A` and `B` with velocities `20 m s^-1` and `30 m s^-1` respectively. The speed of the body at the mid-point of `A` and `B` is.

Options

A. `24 ms^(-1)`
B. `25 ms^(-1)`
C. `25.5 ms^(-1)`
D. `10sqrt(6) ms^(-1)`

Answer

C

Explanation

`a=(V_(B)^(2)-V_(A)^(2))/(2 xx 2x)=(900-400)/(4x)=(125)/(x)`
`:. V_(c)=sqrt(V_(B)^(2)+2ax)`

`= sqrt(400+2 xx(125)/(x) xx x)= sqrt(650)=25.5 m//s`.