A bullet travelling with velocity 60m/s penerates a trunk and comes to rest covering 0.5m. calculate the time taken during the retardation

Answer 1

average velocity=30m/s
time=distance/avgvelocity=.5m/(30m/s)=1/60 th second

Answer 2

V^2 = Vo^2 + 2a*d = 0,
60^2 + 2a*0.5 = 0,
a = -3600 m/s^2.

V = Vo + a*t = 0,?.
60 + (-3600)t = 0,
t = ?.