In a certain time interval the velocity reduces from 72 km per hour to 36 kilometre per hour of car if the car covers a distance of 150 metre during this time interval find the retardation of the car
Assuming the acceleration and retardation remain constant in both case.
Case I:
Initial velocity u=36 km/h=36*1000/3600=10 m/s.
Final velocity v=72 km/h=72*1000/3600=20 m/s.
v=u+at
a=(v-u)/t=(20–10)/5=2 m/s^2
So acceleration = 2 m/s^2
Case II:
Initial velocity u =72 km/h= 20 m/s
Final velocity v= 0 m/s
a=(v-u)/t=(0–20)/20=-1 m/s^2
acceleration= -1 m/s^2
retardation/deceleration= +1 m/s^2