Question

viteza unui obuz cu masa de 40kg sa micsorat de la 800m/s pina la 400m/s.cu cit sa modificat energia cinetica?

Answer 1

[tex]m=40 \ kg \\ v_1=800 \ m/s \\ v_2=400 \ m/s \\ \boxed{\triangle E_c-?} \\ \bold{Rezolvare:} \\ \boxed{E_c= \frac{m \cdot v^2}{2}} \\ \triangle E_c=E_{c1}-E_{c2} \\ E_c_1= \frac{m \cdot v_1^2}{2} = \frac{40 \ kg \cdot (800 m/s)^2}{2} =12 \ 800 \ 000 \ J; \\ E_{c2}= \frac{m \cdot v_2^2}{2} = \frac{40 \ kg \cdot (400 \ m/s)^2}{2} =3 \ 200 \ 000 \ J \\ \triangle E_c=12 \ 800 \ 000 \ J-3 \ 200 \ 000 \ J \\ \Rightarrow \boxed{\trinagle E_c=9 \ 600 \ 000 \ J}.[/tex]