Question

qual energia cinetica de um automovel de massa 800kg com v=72km/h?

Answer 1

E = m*v^2 / 2

1J = 1kg * 1(m^2/s^2)

v = 72km/h = (72/3,6)m/s = 20m/s

E = m*v^2 / 2

E =800kg*(20m/s)^2 / 2 = 400kg* 400(m/s)^2 = 160.000 J