$A$ motorcar of mass $1200\, kg$ is moving along a straight line with a uniform velocity of $90\, km/h$. Its velocity is slowed down to $18\, km/h$ in $4\, s$ by an unbalanced external force. Calculate the acceleration and change in momentum. Also,calculate the magnitude of the force required.

• A
  $ -8\, m/s^2$ and $ -30000\, kg\, m/s$,$2000\, N$
• B
  $ -1\, m/s^2$ and $ -28000\, kg\, m/s$,$8000\, N$
• C
  $ -5\, m/s^2$ and $ -24000\, kg\, m/s$,$6000\, N$
• D
  $ -2\, m/s^2$ and $ -42000\, kg\, m/s$,$5000\, N$