Question

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

Answer 1

Dados:

m = 5 000 g ÷ 1 000 ⇒ 5 kg

v = 72 km/h ÷ 3,6 ⇒ 20 m/s

Ec = ?

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$\grand\boxed{Ec \ = \ \frac{m \ * \ v^{2} }{2} }} \ \ \rightarrow \ \ Fo{\´}rmula.$

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$Ec \ = \ \frac{m \ * \ v^{2} }{2}$

$Ec \ = \ \frac{5 \ * \ 20^{2} }{2}$

$Ec \ = \ \frac{5 \ * \ 400}{2}$

$Ec \ = \ \frac{2 \ 000}{2} \ \ \Rightarrow \ \ \boxed{Ec \ = \ 1 \ 000 \ J}$

Answer 2

$\sf m=5000\,g$

$\sf m=5\,kg$

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

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

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

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

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

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