Răspuns :
Ec=[tex] \frac{m* v^{2} }{2} [/tex]
9=[tex] \frac{m* 15^{2} }{2} \ \textless \ =\ \textgreater \ 9= \frac{m*225}{2} =\ \textgreater \ 225m=9*2=18=\ \textgreater \ m= \frac{18}{225}= 0,08 kg[/tex]
9=[tex] \frac{m* 15^{2} }{2} \ \textless \ =\ \textgreater \ 9= \frac{m*225}{2} =\ \textgreater \ 225m=9*2=18=\ \textgreater \ m= \frac{18}{225}= 0,08 kg[/tex]