A car starts from rest and moves with a uniform acceleration for 2 s. After that it starts to move with a uniform deceleration of `4 m//s^2`. The acceleration of the body if it takes 3 s for the car to stop is

Options

A. `4 m//s^2`
B. `6 m//s^2`
C. `12 m//s^2`
D. none

Answer

B

Explanation

`v = u + at`
`implies v = a xx 2 " " ...(i)`
`implies 0 = v - 3 xx 4 ` (for the case of deceleration)
`= v = 12`
`implies 12 = a xx 2` from (i)
`implies a = 6 m/(s^2)`