Jawabanmu

2014-04-15T21:44:30+07:00
W = F.s = 12.6 = 72 J 
W = ΔEk = 1/2 mv² = 1/2.4.v²=72 
v = √72/2 = √36 = 6 m/s
36x4 bukan 72, tapi 144
Komentar sudah dihapus
:)
2014-04-15T21:49:57+07:00
F=m.a
12N = 4kg . a
3 m/s" = a

Vt" = Vo" + 2.a.s
Vt" =  0 + 2.3.6
Vt" = 36
Vt = 6 m/s

jadi jwbnya 6, klo gk kliru caranya, =D