Retardation Calculation:
The retardation of the car can be calculated using the formula:

retardation = (final velocity - initial velocity) / time taken

Here, the initial velocity is 60 m/s, final velocity is 0 m/s, and time taken is 5 s.

retardation = (0 - 60) / 5
retardation = -12 m/s^2

Therefore, the retardation of the car is -12 m/s^2.

Distance Calculation:
To calculate the distance travelled by the car in 15 s, we need to find the distance travelled during the first 10 s at a velocity of 60 m/s and the distance travelled during the next 5 s while coming to rest.

Distance travelled during the first 10 s:
The distance travelled during the first 10 s can be calculated using the formula:

distance = velocity x time

Here, the velocity is 60 m/s and time is 10 s.

distance = 60 x 10
distance = 600 m

Therefore, the distance travelled during the first 10 s is 600 m.

Distance travelled during the next 5 s:
The distance travelled during the next 5 s can be calculated using the formula:

distance = (initial velocity x time) + (1/2 x acceleration x time^2)

Here, the initial velocity is 60 m/s, time is 5 s, and acceleration is -12 m/s^2.

distance = (60 x 5) + (1/2 x -12 x 5^2)
distance = 300 - 150
distance = 150 m

Therefore, the distance travelled during the next 5 s is 150 m.

Total Distance travelled in 15 s:
The total distance travelled by the car in 15 s is the sum of the distances travelled during the first 10 s and the next 5 s.

total distance = 600 + 150
total distance = 750 m

Therefore, the car travels a total distance of 750 m in 15 s.

T = 15 sec v=0 u=60m/sa=?s=?
v=u + at 0=60+15a-60=15a-60/15=aa=-60/15a=-4
s=ut +1/2at2s=60×15+1/2×(-4)×15×15s=900+450s=1350m