Respostas

2014-08-04T19:40:51-03:00
72 km/h / 3,6 = 20 m/s
V = S/T
20 = 50/T
T = 50/20
T = 2,5 S
2014-08-04T19:43:44-03:00
V² = vo² + 2ad
0 = 20²-2a.50
a = 
4 m/s²

v = vo-.at
0 = 20-4t
20 = 4t
t = 5s

Lembrando que 72km/h equivale a 20m/s.