An object moves the first half of the total distance with a speed of 2 m `s^(-1)` . If the average of the body is ` 3m s ^(-1)` , the speed of the body when it travelles the remaining distance is _______ ` m s^(-1)`

Options

A. 3
B. 6
C. 4
D. 2

Answer

B

Explanation

Let the total distance be 2d.
Then `d/t_(1) =2`
` d/t_(2) =x`
`(2d)/(t_(1)+t_(2)) = 3Rightarrow d= (3(t_(1) +t_(2)))/2`
form (1) and (2)
` 2t_(1)=3((t_(1)+t_(2)))/2 Rightarrow 4t_(1) = 3t_(1) +3t_(2)`
` t_(1) = 3t_(2) therefore d/(t_(1//3)) = x Rightarrow (3d)/t_(1) =x`
form (1) ,
3 (2) =x
` x= 6 m s^(-1)`