To calculate the magnitude of the car's acceleration, we can use the formula:
a = (vf - vi) / t
where a is the acceleration, vf is the final velocity (0 m/s in this case, since the car comes to a stop), vi is the initial velocity, and t is the time.
We know the initial velocity is vf = (distance / time) = (104 m) / (5.3 s) = 19.6 m/s
We know the time is t = 4s
Plugging these values into the formula, we get:
a = (0 - 19.6 m/s) / 4 s = -4.9 m/s^2
The negative value of the acceleration means that the car is slowing down.
The magnitude of the acceleration is 4.9 m/s^2.