Question

qual a energia cinética de uma partícula de massa 5000gente cuja velocidade vale 72km/h?

Answer 1

$Ec = m.v^2/2 = 5000.10^{-3}.(20)^2/2 = 5.400/2 = 5.200 = 1000 J$

Answer 2

$\sf m=5000\,g$

$\sf m=5\,kg$

$\sf v=72\,km/h$

$\sf v=20\,m/s$

$\sf E_c=\dfrac{1}{2}\cdot m\cdot v^2$

$\sf E_c=\dfrac{1}{2}\cdot5\cdot20^2$

$\sf E_c=2{,}5\cdot400$

$\boxed{\boxed{\sf E_c=1000\,J}}$