Given,
Initial Velocity =4 m/s
Acceleration =−2 m/s2
t=4 s
Now,
v=u+at
v=u−2t
At t=2 s, v=0
For t=0 to t=2, particle moves along +ve x− direction and for t=2 to t=4, particle moves along −ve x− direction.
So, total distance travelled,
v2−u2=2as
s=(42)2×2=4 m
total distance travelled =2s=8 m