Question

EXAM TOMORROW !!!
A body starts from rest and attains a velocity of 12m/s in 30 seconds. If final velocity becomes 8m/s. What will be the retardation after 5 seconds ?

Answer 1

ATQ
u=0 v=12m/S t=30 sec
a=v-u/t
=12-0/30
=12/30
=0.4m/s^2
Now retardation
=v=8 m/S u=12m/S t=5
a=v-u/t
=8-12/5
=-4/5
=-0.8 m/s^2

Answer 2

retardation is always negative

so ans will be negative only