Question

qual a energia cinetica de uma particula de massa 5000g cuja velocidade vale 72km/h?

Answer 1

Ec=m*v²/2
m=5000g---5kg
v=72km/h---20m/s
Ec=5*20²/2
Ec=1000J

Answer 2

$\sf m=5000\,g$

$\sf m=5\,kg$

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

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

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

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

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

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