We know that
• The initial velocity is 20 m/s.
,
• The acceleration is -5 m/s^2.
,
• The final velocity is zero because it stops.
,
• The time spent to stop is 4 seconds.
Let's use the following formula.
Using the given magnitudes, we have
Let's solve for d.
Therefore, the car stops 40 meters away after stepping on the brakes.