Question

A car is traveling with a velocity of 80km/h slowed down to 44km/h in 15s. The retardation is????

Answer 1

negative acceleration is called retardation
acceleration (a) = dv/dt
dv=change in velocity
dv= 44-80
dv=-36
dt=15
acceleration (a) = dv/dt
a= -36/15
a= -2.4km/hr
here acceleration is negative so it is called retardation

Answer 2

u=80 km/hr
 =200/9 m/s
v=44 km/hr
 =110/9 m/s
t=15 s
a=v-u/t
( 110/9-200/9)/15
=-10/15
=-2/3 m/s^2(the acceleration is in retardation)