(a)
mass of the car: m=950 kg
Initial speed:
Final speed: (the car comes to rest)
distance:
We can find the acceleration by using the following SUVAT equation:
Re-arranging it and replacing the numbers, we find the acceleration
So now we can calculate the force using Newton's second law:
And the negative sign means the force is applied against the direction of motion.
(b)
In this case, the distance is different:
so, the acceleration in this case is
And so, the force applied in this case is
which is much larger than the force exerted in the previous exercise.