The acceleration of the car running at 12m / S is 5m / S ^ 2 after emergency braking, and the displacement within 6S after ball braking

The acceleration of the car running at 12m / S is 5m / S ^ 2 after emergency braking, and the displacement within 6S after ball braking

How many seconds does the car stop after braking
12/5=2.4s
So 6 seconds is confusion, 2.4 seconds is effective displacement
0.5*5*2.4^2