# Question #afec9

Dec 1, 2016

$- 0.75 m {s}^{-} 2$

negative value indicates slowing down or deceleration or retardation.

#### Explanation:

Kinematic equation connecting values of interest is
$v = u + a t$
where $u \mathmr{and} v$ are the initial and final velocities respectively, $a$ is acceleration and $t$ is time taken for the change. It is assumed that we are dealing with constant acceleration.

Inserting given values we get
$15 = 24 + a \times 12$
Rearranging and Solving for $a$ we get
$12 a = 15 - 24$
$\implies a = - {\cancel{9}}^{3} / {\cancel{12}}_{4}$
$\implies a = - 0.75 m {s}^{-} 2$

As expected negative value indicates slowing down or deceleration or retardation.