Respostas

2014-06-11T19:46:59-03:00
V=72 km/h ou 20 m/s
t=4s
a=?
V=Vi+a.t
0=20+a.4
-4a=20
a=20/4
a=-5 m/s²
V²=Vi²+2.a.s
0=20²+2.-5.s
0=400-10s
10s=400
s=400/10
s=40m