Question

Qual é a energia cinética de um brinquedo com massa de 1,2 Kg, que foi arremessado a uma velocidade de 20 m/s.?
(A) 240J
(B) 100J
(C) 50J
(D) 15J

Answer 1

Ec = m.v²/2

Ec = 1,2.(20)² / 2

Ec = 1,2.400 / 2

Ec = 480 / 2

Ec = 240 J (letra A)

Answer 2

$\Large\displaystyle\text{ \begin{gathered} \hookrightarrow\boxed{\boxed{\bf{ E_C= 240~J }}} \end{gathered} }$

• Explicação:

$\Large\displaystyle\text{ \begin{gathered} \sf{E_C = \dfrac{m \cdot{v} {}^{2} }{2} } \end{gathered} }$

$\Large\displaystyle\text{ \begin{gathered} \sf{E_C = \dfrac{1,2 \cdot20 {}^{2} }{2} } \end{gathered} }$

$\Large\displaystyle\text{ \begin{gathered} \sf{E_C = \dfrac{1,2 \cdot400}{2} } \end{gathered} }$

$\Large\displaystyle\text{ \begin{gathered} \sf{E_C = \dfrac{480}{2} } \end{gathered} }$

$\Large\displaystyle\text{ \begin{gathered} \boxed{\boxed{\sf{E_C =240 \: J }}} \end{gathered} }$