Réponse :
[tex]∆Ec = Ec_{B} - Ec_{A} \ \\ _{A - - > B} \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: [/tex]
[tex]∆Ec = \frac{1}{2} \times 900 \times {130}^{2} - \frac{1}{2} \times 900 \times {90}^{2} [/tex]
[tex] = \frac{900 \times 16900}{2} - \frac{900 \times 8100}{2} [/tex]
[tex] = \frac{15210000}{2} - \frac{7290000}{2} [/tex]
[tex] = \frac{15210000 - 7290000}{2} [/tex]
[tex] = \frac{7920000}{2} [/tex]
[tex]∆Ec = 3 \: 960 \: 000J[/tex]
Explications :
[tex]∆Ec = Ec_{B} - Ec_{A} = sommeW(Fext) [/tex]
A--->B
2. on sait que :
[tex]Ec = \frac{1}{2} \times m \times {v}^{2} [/tex]
