Force = (mass) x (acceleration).
We know the force and the mass, so we can write
6,000 N = (1,200 kg) x (acceleration).
Divide each side by 1,200 kg:
Acceleration = 6000N/1200kg = 5 m/s² .
That's the acceleration. The car's speed changes by 5 m/s each second
that the force acts on it. If the force pushes from behind, then the car goes
5 m/s faster every second. If the force pushes from in front, then the car
goes 5 m/s slower every second.
The car is moving at 10 m/s and we want to slow it down to zero m/s. So
the force has to push from the front, and it will take (10/5) = 2 seconds to
complete the job.
