Respostas

2013-11-12T10:12:57-02:00
Ec = m x v² /2
Ec = 80 x v² / 2
Ec = 40 x v²
8000 = 40 x v²
8000/ 40 = v²
v² = 200
v= raiz de 200
v = 14,14 m/s