Question

ce masa are un corp cu Ec de 200j cu viteza de 2m/s

Answer 1

$E_c=200 \ J \\ v=2 \ m/s \\ E_c=\frac{m \cdot v^2}{2} \ \Rightarrow m \cdot v^2=2E_c \ \Rightarrow m=\frac{2E_c}{v^2} \\ m=\frac{2 \cdot 200 \ J}{(2 \ m/s)^2}=\frac{400 \ J}{4 \ m^2/s^2}=\boxed{100 \ kg}$